JPH0565587A - Aluminum alloy rolled sheet for forming and its production - Google Patents

Abstract

PURPOSE:To provide an Al alloy rolled sheet for forming excellent in formability as well as baking hardenability and used for an automobile body sheet or the like. CONSTITUTION:The objective Al alloy rolled sheet contains >1.2 to 1.5% Si, 0.15 to 1.5% Mn and 0.3 to 1.5% Cu, in which the content of Fe is controlled to <0.2%, that of Mn, Cr, Zr and V each to <0.05% and their total to <0.1% and whose electric conductivity is regulated to <=50% and the average grain size on the surface to <=100mum. As for its manufacturing method, heating before hot rolling is executed at 480 to 560 deg.C, and immediately after its carrying-out from a heating furnace, through the hot rolling, its residence time at 480 to 400 deg.C is regulated to <=30min. Moreover, soln. treatment is executed at 480 to 560 deg.C for <=60sec at >=5 deg.C/sec temp. raising and cooling rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolled aluminum alloy sheet for forming and a method for producing the same, and particularly to applications where high formability and high strength are required and baking is used, for example, automobile body sheets. The present invention relates to a rolled aluminum alloy plate for forming, which is suitable for various forming parts, electric parts, articles, etc., and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, cold-rolled steel sheets have often been mainly used for automobile body sheets, but recently, due to the demand for weight reduction of vehicle bodies, the use of rolled aluminum alloy sheets has been studied. Car body sheet,
Since it is used after being press-molded, it is required to have excellent moldability, in particular to have excellent elongation and bulging properties, and to avoid the occurrence of Luders marks during molding, and it has high strength. This is also essential, and particularly from the point of view of applying bake coating, it is required to have excellent bake hardenability so that high strength can be obtained after bake coating. In addition, it is also required that the coating film has good adhesion at the time of coating and good corrosion resistance after coating.

By the way, there are various aluminum alloy sheets conventionally used for molded products requiring strength, and the main ones are classified as follows depending on the alloy component system.

(A) 5052 alloy (Mg 2.2-2.8%, Cr 0.15) which is a non-heat treatment type Al-Mg alloy.
.About.0.35%, balance Al and unavoidable impurities) O material or 5182 alloy (Mn 0.20 to 0.50)
%, Mg 1.0 to 5.0%, balance Al and unavoidable impurities) O material.

(B) 2036 alloy (Cu 2.2 to 3.0%, Mn 0.1 to 0.1) which is a heat treatment type Al-Cu alloy.
0.4%, Mg 0.3-0.6%, balance Al and unavoidable impurities) T4 treated material or T6 treated material.

(C) Heat treatment type Al-Mg-Zn-Cu
T4 treated material of system alloy. Examples of aluminum alloys of this type include those disclosed in JP-A-52-141409, JP-A-53-103914, and JP-A-57-9.
There is an alloy of No. 8648. Furthermore, Nikkei New Material April 7th, 1986 issue (No. 8) 63-72.
Page, especially page 64, Al-4.5% Mg-
0.38% Cu-1.46% Zn-0.18% Fe-
There is also a 0.09% Si alloy.

(D) 6009 alloy (Mg 0.4 to 0.8%, Si0.
6-1.0%, Cu 0.15-0.6%, Mn 0.2-
T4 treated material with 0.8%, balance Al and unavoidable impurities, and the same 6010 alloy (Mg 0.6 to 1.0%, Si)
0.8-1.2%, Cu 0.15-0.6%, Mn0.
2-0.8%, balance Al and unavoidable impurities) T4
Processing material. These are described in detail in Japanese Examined Patent Publication No. 59-39499, and in addition to these, Japanese Examined Patent Publication No. 61-15
There is an AC120 alloy T4 treated material proposed in No. 148.

However, it has been difficult for these conventional aluminum alloys to sufficiently satisfy all of the above-mentioned properties required for automobile body sheets.

That is, the alloy (a) has a problem that the strength is insufficient and that Luders marks are likely to occur during the molding process, and further that the strength is lowered by the coating baking process. In addition, the alloy (b) has a problem that the formability is poor and the strength is lowered by the coating baking process. Further, the alloy of (C) has a problem that the formability, especially bendability is not sufficient, and the strength is lowered in the coating baking process. In the case of the (d) type alloy, for example, 6009 alloy has insufficient strength, while
In No. 10 alloy, elongation and bendability were insufficient.

Therefore, the present inventors have already disclosed in Japanese Patent Laid-Open No. 61-20.
1748 and Japanese Patent Laid-Open No. 61-201749, Al-M capable of satisfying the above-mentioned various properties to a large extent.
A g-Si-Cu based alloy is proposed.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The Al-Mg-Si-Cu alloys proposed in Japanese Patent Application No. 01748 and Japanese Patent Application Laid-Open No. 61-201749 can satisfy various properties required for an automobile body sheet to a considerable extent, but have bake hardenability and molding. In terms of sex, further improvement is desired. That is, Al-M as in the above proposals
The g-Si-Cu alloy has bake hardenability and has a characteristic that the strength is improved at the time of bake coating, but generally, when trying to improve the formability, the bake hardenability decreases, When it is attempted to improve the bake hardenability, the crystal grains tend to be coarsened and the formability tends to decrease.Therefore, it is difficult to satisfy both the higher bake hardenability and the excellent formability at the same time. Was there.

The present invention has been made in view of the above circumstances, and is an aluminum alloy rolled sheet having excellent bake hardenability, high strength after coating baking, and excellent formability, and a method for producing the same. It is intended to provide.

[0013]

In order to solve the above-mentioned problems, the rolled aluminum alloy plate of the invention of claim 1 has the following constitution.

That is, it contains more than 1.2% of Si and 1.5% or less, Mg of 0.15% or more and 1.5% or less, Cu of 0.3% or more and 1.5% or less, and Fe content of 0.2%. Less than,
Mn amount less than 0.05%, Cr amount less than 0.05%, Z
The amount of r is regulated to less than 0.05%, the amount of V is regulated to less than 0.05%, and the total amount of Mn, Cr, Zr, and V is 0.1.
It is characterized in that it is regulated to less than 0%, the balance is made of Al and inevitable impurities, the conductivity is 50% IACS or less, and the average crystal grain size on the surface is 100 μm or less.

Further, the inventions of claims 2 and 3 define a method for manufacturing an aluminum alloy rolled plate which solves the above-mentioned problems, and the manufacturing method of the invention of claim 2 is Si1.2%. Over 0.1%, Mg 0.15
% To 1.5% inclusive, Cu 0.3% to 1.5% inclusive, Fe amount less than 0.2%, Mn amount 0.05
%, Cr content is less than 0.05%, Zr content is 0.05%
And V content is regulated to less than 0.05%, and M
The total amount of n, Cr, Zr, and V is regulated to less than 0.10%, and a molten aluminum alloy having the balance of Al and inevitable impurities is cast by a semi-continuous casting method, and the obtained ingot is 480 to 560. Start the hot rolling after heating to a temperature in the range of ℃, and the time from immediately after the ingot is discharged from the heating furnace to 400 ℃ or less through the process of hot rolling within 30 minutes. It is characterized in that a hot-rolled sheet having a conductivity of 50% IACS or less and an average grain size of 100 μm or less on the surface is obtained by hot rolling.

The manufacturing method according to the third aspect of the invention is based on Si
More than 1.2% and 1.5% or less, Mg 0.15% or more 1.
5% or less, Cu 0.3% or more and 1.5% or less, Fe amount less than 0.2%, Mn amount less than 0.05%, C
The amount of r is less than 0.05%, the amount of Zr is less than 0.05%, the amount of V is less than 0.05%, and Mn, Cr,
The total amount of Zr and V was regulated to less than 0.10%, and a molten aluminum alloy containing the balance of Al and unavoidable impurities was cast by a semi-continuous casting method, and the obtained ingot was 48
The time from when hot rolling is started after heating to a temperature in the range of 0 to 560 ° C. and immediately after the ingot is discharged from the heating furnace to 400 ° C. or less through the process of hot rolling is 30
After hot rolling for less than a minute and then cold rolling, the solution is heated within a range of 480 to 560 ° C. at a temperature rising rate of 5 ° C./sec or more and subjected to solution treatment within 60 sec. 5
Quenching at a cooling rate of ℃ / sec or more, which results in a conductivity of 50% IACS or less and an average crystal grain size of 100
It is characterized in that a rolled plate having a thickness of μm or less is obtained.

[0017]

First, the reasons for limiting the components in the rolled aluminum alloy plate of the present invention will be described.

Si: Si coexists with Mg to form Mg ₂ S
It is effective to generate i and improve the strength by precipitation hardening, and at the same time, it is effective to improve the formability, especially the elongation. In the case of this invention, Cu which is effective in improving the strength
Since Si is added in an amount of 0.3% or more, the required strength can be obtained when Si exceeds 1.2%, while Si is 1.5%.
If it exceeds%, the effect of improving strength is saturated. Therefore S
i was set within the range of more than 1.2% and 1.5% or less.

Mg: Mg forms Mg ₂ Si and gives strength by coexisting with Si as described above. If the content of Mg is less than 0.15%, the effect of improving the strength is insufficient, while if it exceeds 1.5%, the work hardening becomes too strong, and the moldability, in particular, the elongation decreases, so 0.15 to 1.5% Within the range of.

Cu: Cu is effective for improving the strength and also for improving the formability, especially the bendability, and the effect is sufficiently exhibited at 0.3% or more, while exceeding 1.5%. If the strength is too high and the formability decreases, 0.3
Within the range of up to 1.5%.

Fe: Fe contributes to refinement of crystal grains, but deteriorates formability, especially bendability. Especially when the amount of Fe is 0.
Since the tendency becomes strong at 2% or more, it is necessary to regulate the Fe content to less than 0.2% in order to obtain excellent moldability.

Mn, Cr, Zr, V: All of these elements make the recrystallized grains finer, but if they are contained in excess, the formability deteriorates. 0.05 for either amount
%, Or if the total amount is 0.10% or more, the formability becomes insufficient. Therefore, it is necessary to regulate the total amount to less than 0.05% and the total amount to less than 0.10%. There is.

The balance of the above components may be Al and inevitable impurities other than the above.

In a normal aluminum alloy, Zn is often contained as an impurity or a positive addition element. However, if Zn is up to 2.0%, formability and bake hardenability are not deteriorated. A Zn content of up to 5% is acceptable. Further, in a general aluminum alloy, a minute amount of Ti or Ti and B may be added for refining the ingot crystal grains, and the aluminum alloy rolled sheet of the present invention also contains a small amount of Ti, or Ti and B. May be. However, if Ti is added, the effect cannot be obtained if it is less than 0.01%, and if it is 0.15% or more, primary crystal Ti
Since Al ₃ crystallizes and impairs formability, Ti is 0.01
It is preferably within the range of 0.15%. Also Ti
When B is added together with it, if it is less than 1 ppm, it has no effect, and if it exceeds 500 ppm, coarse particles of TiB ₂ are mixed to impair the formability, so B is preferably in the range of 1 to 500 ppm. Furthermore, in the aluminum alloy of the present invention, a trace amount of Be may be added and contained. Be is added in order to suppress the oxidation of the molten metal particularly when melting an alloy containing Mg and to prevent impurities such as oxide particles from being mixed into the material. However, 10
Even if Be is added in excess of 0 ppm, the effect is saturated and it becomes economically meaningless.

The rolled aluminum alloy sheet of the present invention defines not only the above-mentioned component composition but also the electrical conductivity and the average crystal grain size on the surface. The reasons for limiting the conductivity and the average crystal grain size on the surface are as follows.

That is, the conductivity is related to the solid solution amount of the alloy element in the matrix, and the larger the solid solution amount is, the lower the conductivity is. Therefore, the conductivity is an index of the solid solution amount. In the aluminum alloy plate of the present invention, it is necessary to keep Mg, Si, and Cu in a solid solution state as much as possible. If the amount of these solid solutions is large, these elements will be deposited as precipitates during baking of the coating, and after the baking of coating, Increases strength. That is, high bake hardenability can be exhibited. When the solid solution amount of Mg, Si and Cu is small and the conductivity exceeds 50% IACS, the increase in strength during coating baking is small and the bake hardenability is poor. In order to obtain sufficient paint bake hardenability, a solid solution amount such that the conductivity is 50% IACS or less is required.

Further, the crystal grain size on the surface is related to the rough skin at the time of molding. If the average crystal grain size is 100 μm or less, the rough skin is small, but if the average crystal grain size exceeds 100 μm, the rough skin becomes remarkable, and a molded product is obtained. Not only does it impair the aesthetic appearance, but in an extreme case, it causes breakage during molding. Therefore, the average crystal grain size on the surface needs to be 100 μm or less.

Next, a method of manufacturing the rolled aluminum alloy plate of the present invention, that is, the method of the inventions of claims 2 and 3 will be described.

First, a melt of an alloy having the above-described composition is melted according to a conventional method, and a semi-continuous casting method (DC casting method).
To form an ingot having a rectangular cross section. The casting speed at this time is not particularly limited, but is usually 25 to 250 mm.
/ Min should be set.

Prior to hot rolling, the obtained ingot is subjected to a homogenizing heat treatment, preferably at a temperature in the range of 480 to 560 ° C. for 0.5 to 48 hours. This homogenizing heat treatment has the purpose of eliminating the inhomogeneity of the ingot and improving the formability as in the case of the production of ordinary aluminum alloys, and in the case of the present invention, particularly during the subsequent solution treatment. In order to assist the solutionizing effect in the solution treatment, the solutionizing element should be solid-solved to some extent, or even if precipitation occurs, it should be a fine precipitate to facilitate the solution treatment during solution treatment. Have. If the temperature in the homogenization heat treatment is lower than 480 ° C or the holding time is shorter than 0.5 hours, the Mg ₂ Si penetration is insufficient and the hardened phase of Mg ₂ Si or the like becomes coarse during heating and holding. However, it becomes difficult to sufficiently perform solution treatment in a short time during the subsequent solution treatment, and as a result, the strength after baking for coating becomes insufficient. On the other hand, if the temperature of the ingot heating exceeds 560 ° C., eutectic melting will occur, and even if the heating time exceeds 48 hours, the economic efficiency will only deteriorate.

After the homogenizing heat treatment as described above, preheating for hot rolling is performed again and then hot rolling is performed immediately. In the preheating just before the hot rolling, the solution state of Mg ₂ Si by the ingot heating as described above is kept as much as possible, and even if Mg ₂ Si is deposited, it is deposited in a fine state, so that the solution treatment is performed. It is necessary to heat within the temperature range of the treatment (480 to 560 ° C.), and it is desirable to heat at the highest possible temperature in the solution treatment temperature range. Note that this preheating need only reach the above temperature for the purpose of hot rolling start rolling, and it is not particularly necessary to actively hold it. In addition, in some cases, after the homogenizing heat treatment, the preheating before the hot rolling can be performed subsequent to the homogenizing heat treatment without once cooling.

Successively, hot rolling is carried out. This hot rolling is carried out immediately after being carried out from the heating furnace for heating until the temperature is lowered from 480 ° C. to 400 ° C. or less through the process of hot rolling. Must be done within 30 minutes. That is, the residence time at a temperature in the range of 480 ° C to 400 ° C needs to be 30 minutes or less. This is to prevent precipitation and coarsening of Mg ₂ Si in the process of hot rolling immediately after unloading from the heating furnace, and to facilitate subsequent solution treatment. Basically, 480-
The residence time at 400 ° C should be within 30 minutes, but M
In order to reliably prevent precipitation and coarsening of g ₂ Si, it is desirable to make the residence time as short as possible.

After hot rolling, the obtained rolled plate may be used as a product plate as it is, but usually, cold rolling is further performed to a predetermined plate thickness, and in that case, hot rolling and cold rolling are performed. Intermediate annealing is performed as necessary during the cold rolling or in the middle of cold rolling. Then, a solution treatment is performed on the rolled plate after cold rolling.

This solution treatment is an important step for solid-soluting Mg ₂ Si etc. in the matrix, thereby imparting bake hardenability to improve the strength after coating baking, and at the same time This is an effective process for improving moldability by crystallization. In order to obtain excellent formability, the average crystal grain size on the plate surface needs to be 100 μm or less as described above, and therefore it is necessary to perform recrystallization so that the recrystallized grain becomes 100 μm or less. In addition, M which is a transition element
Since n, Cr, Zr, and V themselves adversely affect the formability, each of these elements is 0.0
An attempt is made to obtain good moldability by limiting the amount to less than 5%, less than 0.10% in total. On the other hand, by carrying out sufficient solution treatment,
In order to obtain sufficient bake hardenability, solution treatment at high temperature for a long time is preferable. However, in the case of this invention, M, which is known as a grain refinement element or a recrystal grain stabilization element, is used.
As described above, the contents of n, Cr, Zr, and V are regulated to a small amount. Therefore, the recrystallized grains become coarse and the grain size of 100 μm or less cannot be obtained in the stabilization treatment at high temperature for a long time. .. Therefore, in the present invention, the temperature rising rate in the solution heat treatment is 5 ° C./sec or more, and the heating temperature is 480 ° C. or more and 560 or more.
The temperature is kept below ℃ and the holding time is within 60 seconds. If the rate of temperature rise is less than 5 ° C / sec, or if the heating temperature exceeds 560 ° C, or if the holding time exceeds 60 sec, the crystal grains become larger than 100 µm and become coarse, deteriorating moldability. Will end up. As described above, from the viewpoint of crystal grains, it is preferable that the temperature rising rate is fast, the strength is low, and the time is short, but when such solution treatment conditions are applied in the conventional general process, the solution Insulation is insufficient, and the conductivity exceeds 50% IACS, and sufficient bake hardenability cannot be obtained. Therefore, in the present invention, the solution treatment can be easily performed by applying the heating-hot rolling conditions as described above, whereby sufficient solution treatment can be achieved even by rapid temperature rising / short time / low temperature solution treatment. Is able to do. That is, by appropriately combining the conditions of heating ~ hot rolling and the solution treatment conditions described above,
For the first time, it became possible to satisfy the formability and the bake hardenability at the same time by setting the crystal grain to 100 μm or less and the conductivity to 50% IACS or less at the same time. The cooling rate during quenching after the solution treatment is important for obtaining bake hardenability, and if it is slower than 5 ° C / sec, the quenching effect is insufficient and the conductivity does not become 50% IACS or less. 5 like this
Forced air cooling, mist quenching, water quenching, etc. are suitable for obtaining a cooling rate of ℃ / sec or more. Further, the solution treatment temperature is preferably low for grain refinement as described above, but if it is lower than 480 ° C., solution treatment is not sufficiently performed.

From the above, the solution treatment condition is 5 ° C./sec.
Heat to 480 to 560 ° C at the above temperature rising rate for 60se
After holding within c, quenching was performed at a cooling rate of 5 ° C / sec or more. In order to achieve such conditions, typically, a coil continuous annealing device (for example, a gas furnace CAL,
An electromagnetic induction heating furnace CAL or the like) may be used.

Incidentally, the intermediate annealing which is performed between the hot rolling and the cold rolling as described above or in the middle of the cold rolling as required may be either batch annealing or continuous annealing. From the viewpoint of solution treatment, continuous annealing is preferable. In the case of continuous annealing, it is suitable that the temperature is within the range of 350 to 560 ° C. without holding or within 3 minutes, preferably within 60 seconds. That is, if the temperature of the intermediate annealing due to continuous annealing exceeds 560 ° C, the crystal grains may become coarse and adversely affect the formability, while if the temperature is less than 350 ° C, recrystallization does not occur. If the holding time exceeds 60 seconds,
If the temperature is 480 ° C. or higher, the crystal grains may be coarsened. However, if the temperature is 480 ° C. or lower, the crystal grains are not coarsened. Within 3 minutes is preferable. On the other hand, in the batch type intermediate annealing, since the heating and holding time is long, it is necessary to pay attention to the coarsening of Mg ₂ Si, and the holding is performed at the temperature within the range of 300 to 400 ° C. for 0.5 to 24 hours. Is appropriate. That is, if the temperature of the batch type intermediate annealing exceeds 400 ° C., Mg ₂ Si may be coarsened, and the solution treatment during the subsequent solution treatment may be insufficient, so that excellent bake hardenability may not be obtained. Also, recrystallization is not performed below 300 ° C. If the holding time is less than 0.5 hours, the production becomes unstable, while long annealing for more than 24 hours only impairs the economical efficiency.

The rolling ratio in cold rolling immediately before the solution treatment is preferably 30% or more. If the cold rolling ratio immediately before the solution treatment is less than 30%, the recrystallized grain size may exceed 100 μm and coarsen.

The rolled plate obtained as described above may be aged at room temperature in accordance with a conventional method, but may be subjected to strain correction such as leveling or skin pass in order to obtain flatness if necessary. In addition, when such strain correction is performed, the purpose is to recover the deterioration of the formability due to it, or to prevent the change in strength over time,
For example, heat treatment as shown in FIGS. 1 and 2 of JP-A-64-11953 may be performed.

When the rolled aluminum alloy sheet of the present invention as described above is actually used, it is usual to perform a forming process such as a press working and then to apply baking coating, and 150 to 250 is applied during baking coating. It is usual to heat at about ° C. In the molding process, as described above, the average crystal grain size on the surface is 100 μm or less, and the contents of Mn, Cr, Zr, V, and Fe are regulated to a small amount, so that the moldability is excellent. Also 50% conductivity
Since Mg ₂ Si and the like are sufficiently solid-solved so as to be not more than IACS, they precipitate during baking coating to increase the strength, and so-called bake hardenability is obtained.

[0040]

EXAMPLES Alloys Nos. 1 to 5 in Table 1 were cast into ingots of 500 × 1200 × 400 mm by a semi-continuous casting method. After subjecting the obtained ingot to homogenization heat treatment at 530 ° C. for 10 hours, as preheating before hot rolling, as shown in Table 2, 530 ° C. for 2 hours or 43
It was heated at 0 ° C. for 2 hours and hot-rolled to a plate thickness of 3 mm. The hot rolling end temperature is 280 ° C when the heating temperature immediately before hot rolling is 530 ° C, and 250 ° C when the heating temperature immediately before hot rolling is 430 ° C. Further, the time required from the carrying out of the heating furnace immediately before hot rolling to the end of hot rolling is 10 minutes. Then, the hot-rolled sheet was cold-rolled to have a sheet thickness of 1 mm, and then subjected to solution treatment using a continuous annealing furnace. The conditions of the solution treatment are 520 ° C. × 10 sec at a heating rate / cooling rate of 30 ° C./sec, or 550 ° C. × 90 sec at a heating rate / cooling rate of 30 ° C./sec.
c.

The electrical conductivity and the average crystal grain size of the surface of each rolled plate after the solution treatment were examined. The results are shown in Table 2 together with the main production conditions. Further, the mechanical properties, the formability, and the bake hardenability of each rolled plate were examined for 7 to 10 days at room temperature, and the results are shown in Table 3. Mechanical properties include proof stress (YS) and tensile strength (T
S) and elongation were investigated. As the moldability, Erichsen value (Er) and 180 ° minimum bending radius were examined. Regarding the bake hardenability, a 175 × 1 hour baking equivalent heat treatment was performed and the yield strength (YS) after the treatment was examined.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

As is apparent from Table 3, using the alloys (alloy numbers 1 to 4) within the compositional range of the present invention, the conductivity was 50% IACS or less, and the average crystal grain size on the plate surface was 100 μm or less. In all cases (Production Codes A to D), the moldability was good, the strength after baking was high, and the excellent bake hardenability was exhibited. On the other hand, when the comparative alloy (Alloy No. 5) containing a large amount of Fe, Cr, and Mn (manufacturing code E) was used, the conditions of conductivity and crystal grain size were satisfied, but the formability was poor. Was there. Further, although an alloy within the compositional range of the present invention (alloy No. 1) is used, when the preheating temperature before hot rolling is lower than 480 ° C. (production code F), the conductivity is 50% IACS. In this case, not only the strength was low, but also the bake hardenability was poor. Also, similarly, the composition is within the range of the present invention (alloy No. 1), but when the solution treatment time is too long (Production Code G), the crystal grains become coarse and the formability is remarkably poor. Was there.

[0046]

EFFECTS OF THE INVENTION The rolled aluminum alloy sheet for forming according to the present invention is excellent in formability and at the same time excellent in bake hardenability. Therefore, forming such as press working can be easily performed and rough skin due to forming can be obtained. Without occurrence,
Moreover, the strength is increased in the baking coating process, and finally a baked coating molded product having remarkably high strength can be obtained. Therefore, the rolled sheet of the present invention is particularly suitable for automobile body sheets. Further, according to the manufacturing method of the present invention, it is possible to easily obtain a rolled plate having excellent performance as described above on a practical scale.

The rolled aluminum alloy sheet of the present invention is most suitable for automobile body sheets as described above, but is used for other forming processing and baking coating.
For example, excellent performance can be exhibited even when used for automobile parts such as wheels, oil tanks, air cleaners, various caps, blinds, aluminum cans, household appliances, instrument covers, chassis of electric equipment, and the like.

Claims (3)

[Claims] 1. Si more than 1.2% (weight%, hereinafter the same) and 1.5% or less, Mg 0.15% or more and 1.5% or less, C
u of 0.3% or more and 1.5% or less, Fe content of less than 0.2%, Mn content of less than 0.05%, and Cr content of 0.
Less than 05%, Zr amount less than 0.05%, V amount of 0.05
%, And the total amount of Mn, Cr, Zr, and V is regulated to less than 0.10%, the balance consisting of Al and unavoidable impurities, conductivity of 50% IACS or less, and average surface A rolled aluminum alloy plate for forming, which is excellent in bake hardenability and formability, having a crystal grain size of 100 μm or less. 2. Si more than 1.2% and 1.5% or less, Mg
0.15% to 1.5%, Cu 0.3% to 1.5
% Or less, Fe content is less than 0.2%, Mn content is less than 0.05%, Cr content is less than 0.05%, Zr content is less than 0.05%, V content is 0.05%. And the total amount of Mn, Cr, Zr, and V is regulated to less than 0.10%, and the balance is made of an aluminum alloy melt composed of Al and unavoidable impurities by a semi-continuous casting method. The time from heating the ingot to a temperature in the range of 480 to 560 ° C and then starting hot rolling, and immediately after carrying out the ingot from the heating furnace to 400 ° C or less through the process of hot rolling. Hot rolling for 30 minutes or less to obtain a rolled plate having an electric conductivity of 50% IACS or less and an average crystal grain size of 100 μm or less on the surface, and bake hardenability and forming. Aluminum alloy pressure for forming with excellent properties Method of manufacturing the plate. 3. Si more than 1.2% and 1.5% or less, Mg
0.15% to 1.5%, Cu 0.3% to 1.5
% Or less, Fe content is less than 0.2%, Mn content is less than 0.05%, Cr content is less than 0.05%, Zr content is less than 0.05%, V content is 0.05%. And the total amount of Mn, Cr, Zr, and V is regulated to less than 0.10%, and the balance is made of an aluminum alloy melt containing Al and unavoidable impurities by a semi-continuous casting method. The time from heating the ingot to a temperature in the range of 480 to 560 ° C and then starting hot rolling, and immediately after carrying out the ingot from the heating furnace to 400 ° C or less through the process of hot rolling. Hot rolling for 30 minutes or less, and then cold rolling, and heating at a heating rate of 5 ° C / sec or more within a range of 480 to 560 ° C for solution treatment within 60 seconds. And quenching at a cooling rate of 5 ° C / sec or more, The average crystal grain size of 0% IACS or less addition surface is characterized by obtaining a rolled sheet is 100μm or less, the production method of the bake hardenability and excellent formability molding an aluminum alloy rolled sheet.