JP2003342665A - Aluminum-magnesium aluminum alloy plate for hot blow molding and hot-blow-molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate material for hot blow molding having suitable hot blow moldability, suppressed in a decrease in the smoothness of molding appearance during hot-blowing, and being excellent in appearance when coated. <P>SOLUTION: The hot-rolled Al-Mg aluminum alloy plate comprises an alloy containing 3.5-6.0 wt.% Mg, containing at least one of 0.5-0.8 wt.% Mn and 0.05-0.20 wt.% Cr, and having an Si content controlled to at most 0.10 wt.%, an Fe content controlled to at most 0.12 wt.%, and a Cu content controlled to at most 0.10 wt.%, and the balance comprising irreversible impurities and is prepared by hot-rolling an ingot after homogenization, cold-rolling the hot- rolled product at a cold rolling rate of at least 25%, subjecting the cold-rolled product to intermediate annealing including heating the product to a temperature range of 400-550°C at a rate of temperature increase of at least 1°C/sec and keeping the product in this state for at longest 5 min, cold-rolling the product at a cold rolling rate of 25 to below 50%, and subjecting the cold-rolled product to the final annealing including heating the product to a temperature range of 400-550°C at a rate of temperature increase of at least 1°C/sec and keeping the product in this state for at longest 5 min. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to Al which is subjected to hot blow molding.
The present invention relates to a Mg-based aluminum alloy plate, particularly a plate material suitable for parts such as automobile body panels where appearance is required, and a hot blow molded product using the same.

[0002]

2. Description of the Related Art Hot blow molding is suitable as a technology suitable for low-volume production of a wide variety of products, because it is cheaper than a cold press molding machine and a manufacturing apparatus, and has a high degree of freedom in molding. The hot blow molding material is required to have fine recrystallized grains of about 10 μm in terms of metal structure.
The characteristic feature of the manufacturing method is that, in order to obtain fine grains, strong cold working is performed before the final rapid thermal annealing. The amount of strain in cold working correlates with the grain size formed in the final annealing step, and the grain size decreases as the strength increases. In actual production, strong working induces edge cracks during rolling, so intermediate annealing is required as appropriate. However, even when intermediate annealing is performed, it is necessary to increase the cold rolling rate before final annealing thereafter. is there.

On the other hand, in automobile body panels, for example, the appearance after painting is required to be a smooth factor in the appearance quality factor. It is known that when cold-pressing is performed using a plate material for cold-pressing, defects called ridging marks, which are mainly due to the anisotropy of the material, occur. And, in the conventional hot blow molding, the phenomenon that the smoothness of the appearance after coating is impaired is recognized similarly to the ridging mark in the case of cold pressing, and the commercial value is greatly reduced. Since the hot blow molding method is a plastic working method that imparts large deformation, even if the material does not show deterioration in smoothness when cold pressing is performed, Since defects similar to ridging marks may occur, conventional hot blow molding materials are unsuitable as materials for automobile body panels.

As a conventional hot blow molding material or a method for manufacturing the same, there are techniques described in Patent Documents 1 to 5, for example.

[0005]

[Patent Document 1] Japanese Patent Laid-Open No. 60-238460

[Patent Document 2] Japanese Patent Laid-Open No. 60-238461

[Patent Document 3] Japanese Patent Laid-Open No. 62-96643

[Patent Document 4] JP-A-7-26342

[Patent Document 5] JP-A-7-305131

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has an appropriate hot blow moldability, and the deterioration of the smoothness of the outer surface of the molded product that occurs during hot blow molding. It is an object of the present invention to provide a hot blow molding plate material and a hot blow molding product which are suppressed and have excellent appearance quality after coating.

[0007]

A first aspect of the invention is to provide a weight ratio of M
g: 3.5-6.0%, and Mn: 0.5-
0.8%, or Cr: 0.05 to 0.20%, 1 or 2 types are contained, and Si content is 0.10%.
Hereinafter, the Fe content is 0.12% or less and the Cu content is 0.
It is regulated to 10% or less and the balance is made of an alloy consisting of Al and unavoidable impurities. The ingot is homogenized, hot-rolled, and cold-rolled at a cold rolling rate of 25% or more to raise the temperature. An intermediate annealing is performed by heating at a speed of 1 ° C / sec or more within a temperature range of 400 ° C to 550 ° C and holding for 5 minutes or less, and after the intermediate annealing, cold rolling of 25% or more and less than 50% to the final plate thickness. Cold rolling at a rate
In the Al-Mg system aluminum alloy plate for hot blow molding, the final annealing is performed by heating the film in a temperature range of 400 ° C to 550 ° C for 1 / sec or more and holding it for 5 minutes or less. Item 1).

As described above, the Al—Mg-based aluminum alloy plate for hot blow molding of the present invention uses an alloy having a specific component composition and adopts the above specific manufacturing method to obtain hot blow moldability. And the reduction of the smoothness of the outer surface of the molded product that occurs during hot blow molding. First, the Al for hot blow molding of the present invention will be described below.
The meaning of the components contained in the alloy forming the Mg-based aluminum alloy plate (hereinafter, appropriately referred to as the aluminum alloy plate of the present invention) and the reasons for limitation will be described.

Mg: 3.5-6.0%; Mg enhances the strength of the product after molding, and promotes dynamic recovery and recrystallization during hot blow molding, which decreases with molding. Make up for sex. The preferred content range is 3.5 to 6.0%, and 3.
If it is less than 5%, the effect of promoting recrystallization is small, and if it exceeds 6.0%, the hot rolling property is impaired.

Mn: 0.5-0.8%, Cr: 0.05
˜0.20%; Mn and Cr stabilize the recrystallized grains during blow molding to provide good moldability and appearance quality after molding, and also increase strength after molding. The preferred contents are 0.5 to 0.8% and 0.
It is in the range of 05 to 0.20%. If both are below the lower limit, the stabilizing effect will be weakened and the crystal grains will become coarse, leading to poor formability and poor appearance quality due to rough skin. If the content exceeds the range, coarse crystallized substances are formed in the ingot, the hot blow moldability is impaired, and the segregated crystallized substances deteriorate the appearance quality after molding. Further, both Mn and Cr do not necessarily have to be contained, and the above effect can be obtained by containing at least one.

Si content 0.10% or less, Fe content 0.12% or less, Cu content 0.10% or less; In the present invention, the content of Fe and Si as impurities is limited to the above amount. It is important to. Impurities Fe and Si form insoluble Al-Fe-Si-based compounds and Mg ₂ Si compounds, and these compounds precipitate at grain boundaries to increase cavities, which deteriorates hot blow moldability and causes molding. It reduces the strength and elongation afterwards. More preferably Fe,
It is preferable to limit Si to 0.05% or less. Also,
Since Cu impairs the hot rolling property, it is important to limit it to 0.10% or less.

Next, in producing the aluminum alloy sheet of the present invention, first, the ingot is subjected to homogenization treatment, hot rolling, and then cold rolling at a cold rolling rate of 25% or more. In this case, if the cold rolling is less than 25%, there is a problem that a desired microstructural change cannot be obtained in the intermediate annealing described later.

After the cold rolling, the heating rate is 1 ° C./se
When heated to a temperature range of 400 ° C to 550 ° C at a temperature of c or higher, 5
Intermediate annealing is performed to hold for less than a minute. This intermediate annealing is
It is necessary as an intermediate treatment to make a non-uniform hot rolling structure a uniform structure in the final plate. Then, during the intermediate annealing, the hot-rolled structure is recrystallized to improve the structure. If intermediate annealing is not performed, the final plate will have a non-uniform structure, and a smooth appearance cannot be obtained after blow molding.

The temperature rising rate in the intermediate annealing is 1
If it is less than ° C / sec, a non-uniform recrystallized structure is formed again and the role of modification is insufficient, and a smooth surface cannot be obtained after blow molding. If the holding temperature is lower than 400 ° C, recrystallization does not occur sufficiently, and if it exceeds 550 ° C, melting may occur. In addition, heat treatment with a holding time of more than 5 minutes
It has little economic significance.

After the intermediate annealing, cold rolling is carried out again to recrystallize by the final annealing to obtain a uniform isotropic structure and a material having excellent smoothness after blow molding. The cold rolling after the intermediate annealing is performed at a cold rolling rate of 25% or more and less than 50% up to the final plate thickness. At this time, if the cold rolling ratio is less than 25%, the desired smoothness cannot be obtained because recrystallization is not performed in the final annealing described later. Further, when it is 50% or more, not only is it economically insignificant, but also when hot-blow forming is performed on the sheet after the final annealing, anisotropy may be generated again and the smoothness of the appearance may be rather deteriorated.

After that, at a temperature rising rate of 1 ° C./sec or more, 4
The final annealing is performed by heating within a temperature range of 00 ° C to 550 ° C and holding for 5 minutes or less. The temperature rising rate of this final annealing is 1
If it is less than ° C / sec, a non-uniform recrystallized structure is formed again and a smooth surface cannot be obtained after blow molding. If the holding temperature during the final annealing is less than 400 ° C, recrystallization does not occur sufficiently, and if it exceeds 550 ° C, melting may occur. Also,
Heat treatment for more than 5 minutes has little economic significance.

The second invention is an aluminum alloy plate,
A hot blow-molded product that has been subjected to hot blow molding in a temperature range of 00 ° C. or higher, wherein the aluminum alloy plate is
In weight ratio, it contains Mg: 3.5-6.0%, and Mn: 0.5-0.8%, or Cr: 0.05.
~ 0.20% of 1 or 2 types, and Si
Content of 0.10% or less, Fe content of 0.12% or less, Cu content of 0.10% or less, balance A
1 and an unavoidable impurity alloy. The ingot is homogenized, hot-rolled, and cold-rolled at a cold rolling rate of 25% or more.
Intermediate annealing is performed by heating within a temperature range of 00 ° C to 550 ° C and holding for 5 minutes or less, and after the intermediate annealing, the final plate thickness is 2
Cold rolling is performed at a cold rolling rate of 5% or more and less than 50%, and then 400 ° C to 550 ° C at a heating rate of 1 ° C / sec or more.
The hot-blow molded article is an Al-Mg-based aluminum alloy plate for hot-blow molding that has been subjected to final annealing for heating within the temperature range of 5 and holding for 5 minutes or less (claim 6). ).

The hot blow molded product of the present invention uses the above-mentioned excellent aluminum alloy plate according to the first invention as a raw material. Therefore, even if this is heated to a temperature of 400 ° C. or higher and hot blow molding is performed, it is possible to significantly suppress the occurrence of defects such as conventional ridging marks.
Therefore, the hot blow molded product of the present invention has extremely excellent smoothness, and can be applied to various products with severe appearance requirements.

A third aspect of the present invention is a hot blow-molded product obtained by subjecting an aluminum alloy plate to cold plastic working and then hot blow molding in a temperature range of 400 ° C. or higher. Are Mg: 3.
5 to 6.0% and Mn: 0.5 to 0.8
%, Or Cr: 0.05 to 0.20%, one or two kinds are contained, and the Si content is 0.10% or less,
Fe content 0.12% or less, Cu content 0.10%
Regulated below, the balance consisting of alloy consisting of Al and unavoidable impurities, the ingot is hot-rolled after homogenization treatment,
Further, cold rolling with a cold rolling rate of 25% or more is performed, and intermediate annealing is performed in which the temperature is raised within a temperature range of 400 ° C. to 550 ° C. at a temperature rising rate of 1 ° C./sec or more and held for 5 minutes or less. After the intermediate annealing, cold rolling is performed at a cold rolling rate of 25% or more and less than 50% to the final plate thickness, and then the temperature rising rate is 1 ° C / sec.
Above, the final annealing is performed by heating within the temperature range of 400 ° C to 550 ° C and holding for 5 minutes or less.
Cold rolling is performed at a cold rolling rate of less than 0%, and then finish heat treatment is performed in which the temperature is raised within a temperature range of 270 ° C to 400 ° C at a temperature rising rate of 1 ° C / sec or more and held for 5 minutes or less. The hot-blow molded article is an Al-Mg-based aluminum alloy plate for hot-blow molding (claim 9).

As described above, the hot blow molded product of the present invention is manufactured by a special molding method in which cold plastic working is performed and then hot blow molding is performed.
Then, as an aluminum alloy plate as a material thereof, the above-described Al—Mg based aluminum alloy plate for hot blow molding of the first invention was further subjected to cold rolling and finishing heat treatment after the final annealing. Use one. As a result, it is possible to easily obtain a smooth appearance without causing defects after cold plastic working.
Since the above hot-blow molded product can maintain excellent quality even after being subjected to cold plastic working and then subjected to hot-blow molding, it has a higher degree of freedom than the case of performing only hot-blow molding. High shape design is possible and the added value of the product can be further enhanced.

Here, when the cold rolling ratio of the cold rolling after the final annealing is less than 25%, the effect of suppressing coarsening during heating before hot blow molding is not sufficient, and exceeds 50%. Therefore, not only is it economically insignificant, but recrystallization before hot blow molding may cause anisotropy again, which may worsen the smoothness of the appearance.

The temperature rising rate of the finish heat treatment is 1 ° C./se
If it is less than c, a non-uniform recrystallized structure is formed again during heating before hot blow molding, and a smooth surface cannot be obtained after hot blow molding. Further, if the holding temperature of the finish heat treatment is less than 270 ° C, it is difficult to guarantee the cold workability before hot blow molding, and if it exceeds 400 ° C, uneven heating is performed again before heating by hot blow molding. It may form a crystalline structure. Also, heat treatment for more than 5 minutes is economically insignificant. The meanings of the other component ranges, the reasons for limitation, the meanings of the conditions in the manufacturing process, and the reasons for limitation are the same as in the case of the first invention described above.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The ingot according to the first aspect of the invention can be obtained by melting and casting an aluminum alloy having the above composition according to a conventional method. The homogenization treatment of the ingot is preferably performed in the temperature range of 450 to 550 ° C, for example. Homogenization temperature is 450 ℃
If it is less than 1, there is a problem that segregation in the ingot cannot be removed and hot workability is deteriorated.
If it exceeds 550 ° C, there is a problem that the slab melts.

The hot rolling start temperature after the homogenization treatment is preferably 250 to 500 ° C., and more preferably 400 ° C. or lower. When the hot rolling start temperature is lower than 250 ° C., there is a problem that the deformation resistance of the material is high and the number of rolling passes is increased, so that there is no economic merit. On the other hand, if it exceeds 500 ° C, it is not desirable because it induces cracks during hot rolling.
It is more preferable that the temperature is not higher than C.

In the present invention, after the hot rolling, the intermediate annealing before cold rolling is carried out by heating in a temperature range of 300 ° C. to 500 ° C. for 1 hour to 10 hours in a batch furnace. Is preferably applied (claim 2). This intermediate annealing before cold rolling is not an essential step, but it is preferable to add it because it can reduce the rolling load in the subsequent cold rolling.

When the intermediate annealing before cold rolling is added, the batch furnace is used as described above and the heating temperature is set to 30.
The range is 0 ° C to 500 ° C. If the heating temperature is less than 300 ° C., there is a problem that the above rolling load reducing effect cannot be obtained. On the other hand, if the heating temperature exceeds 500 ° C,
Mg is concentrated on the surface layer, and a Mg oxide layer is formed on the plate surface.
There is a problem that the surface quality is significantly deteriorated. Also,
If the holding time is less than 1 hour, the rolling load reducing effect cannot be obtained. On the other hand, if the holding time exceeds 10 hours, the same problem as in the case where the heating temperature exceeds 500 ° C. is likely to occur. Further, even if it is held for 10 hours or more, the rolling load reducing effect does not change and the industrial cost increases.

Further, in the present invention, it is preferable that the alloy further contains Be: 20 to 80 ppm (claim 3). In this case, as in the case of a normal Al-Mg-based alloy, it is possible to prevent the oxidation of the molten metal and prevent the abnormal appearance quality caused by the inclusion of the oxide in the ingot. When the content of Be is less than 20 ppm, such an antioxidant effect is not obtained so much, while when it exceeds 80 ppm, the effect is saturated and there is a problem that it is not desirable in the environment.

After the final annealing, cold rolling is further performed at a cold rolling rate of 25% or more and less than 50%,
Then, at a temperature rising rate of 1 ° C / sec or more, 270 ° C to 400 ° C.
It is preferable to perform a finishing heat treatment for heating within a temperature range of ° C and holding for 5 minutes or less (claim 4). In this case, it is possible to more effectively improve the hot blow moldability and suppress the deterioration of the smoothness of the outer surface of the molded product that occurs during the hot blow molding. And, it is very effective for improving hot blow moldability especially in applications where cold working is applied before hot blow molding.

When the cold rolling ratio of the cold rolling after the final annealing is less than 25%, the effect of suppressing coarsening during heating before hot blow molding is not sufficient, and when it exceeds 50%, it is economical. Not only is it of little significance, but recrystallization before hot blow molding may cause anisotropy again, which may worsen the smoothness of the appearance.

The temperature rising rate of the finishing heat treatment is 1 ° C./se
If it is less than c, a non-uniform recrystallized structure is formed again during heating before hot blow molding, and a smooth surface cannot be obtained after hot blow molding. Further, if the holding temperature of the finish heat treatment is less than 270 ° C, it is difficult to guarantee the cold workability before hot blow molding, and if it exceeds 400 ° C, uneven heating is performed again before heating by hot blow molding. It may form a crystalline structure. Also, heat treatment for more than 5 minutes is economically insignificant.

The plate material is preferably a vehicle body panel material for automobiles (claim 5). Automotive body panel materials require sharpness after painting. The sharpness is strongly influenced by the appearance of the molded product, especially the smoothness, and the flatter the sharpness, the higher the sharpness. The smoothness of the surface of the molded product is achieved by uniformly deforming the material during hot blow molding. Non-uniform deformation occurs during hot blow molding in molded products with poor image clarity. This is due to the non-uniformity of the metallographic structure of the plate before blow molding. These inhomogeneities are
The non-uniform recrystallization structure that occurs during hot rolling and strong cold rolling have an influence. In this respect, by applying the above-mentioned excellent aluminum alloy sheet of the present invention to the above-mentioned automobile body panel material, the non-uniformity of the metal structure can be prevented and an excellent sharpness can be realized. Can be obtained. Further, the vehicle body panel for automobiles includes, for example, so-called outer materials such as a hood hood, a trunk lid, a roof, a door, and other various inner materials that are required to have external appearance characteristics.

Next, in the above second and third inventions,
The Al—Mg-based aluminum alloy plate for hot blow molding is processed in a batch furnace at 30% after hot rolling.
It is preferable to perform intermediate annealing before cold rolling in which the material is heated within a temperature range of 0 ° C to 500 ° C and held for 1 hour to 10 hours (claims 7 and 10). In this case, as described above, the effect of reducing the rolling load of cold rolling after hot rolling in the manufacturing method can be obtained.

In the second aspect of the invention, the Al-Mg based aluminum alloy sheet for hot blow molding is further cooled at a cold rolling rate of 25% or more and less than 50% after the final annealing. Hot rolling, then heating rate 1 ℃
It is preferable that a finishing heat treatment is performed in which the heat treatment is performed within a temperature range of 270 ° C. to 400 ° C. for at least 5 sec / sec and holding is performed for 5 minutes or less (claim 8). In this case, it is possible to obtain a hot blow-molded product having even better smoothness.

Also in the above second and third inventions,
For the same reason as above, the alloy further has Be: 20-
It is preferable to contain 80 ppm (claim 11).
Further, it is preferable that the hot blow molded product is a vehicle body panel for an automobile (claim 12). That is, as described above, the hot-blow-molded product can maintain excellent quality even after being subjected to cold plastic working and then hot-blow molding. It also enables highly flexible shape design. Therefore, it can be easily applied to the vehicle body panel for which design is important.

[0035]

Example (Example 1) In this example, as shown in Table 1,
Six types of aluminum alloy plates as the products of the present invention (Sample E
11 to E16) and four kinds of aluminum alloy plates (samples C11 to C11) as a comparative product whose component range is out of the range of the present invention.
C14) was prepared and its characteristics were compared.

[0036]

[Table 1]

First, slabs of alloy components shown in Table 1 were manufactured by semi-continuous casting. These alloys were homogenized by holding them at 500 ° C. for 8 hours, after being faced, heated to 395 ° C. and hot-rolled to obtain 3.9 mm hot-rolled sheets. Next, cold rolling (cold rolling rate 50
%) → intermediate annealing (heating rate 10 ° C./sec, holding temperature 5)
00 ℃, holding time 30 seconds → cold rolling (cold rolling rate 33
%) → final annealing (heating rate 10 ° C./sec, holding temperature 5)
The aluminum alloy plate having a thickness of 1.3 mm was obtained by sequentially performing (00 ° C., holding time 30 seconds).

Next, the obtained aluminum alloy plate was
A test piece was cut out into a square of 0 mm square, and hot blow molding was actually performed. Specifically, the test piece
Heating to 0 ℃, 250mmW × 250mmL × 65m
Hot blow molding was performed by a female mold into a square tube shape of mH. The wall thickness of the central portion of the bottom surface was 0.85 mm, and the wall thickness reduction rate was about 34.6%.

Next, the mechanical properties of the center portion of the obtained rectangular tube molded product were measured by a tensile test. Similarly, a 100 mm square test piece was cut from the center, pickled, and then painted on a general automobile, and the quality (sharpness) of the coating film was evaluated with a tension meter.

Here, the evaluation of the tension meter is as follows.
As shown in FIG. 1, the image capturing device 5 is used. The imaging device 5 includes a TP storage section 51 that covers the test piece 1, a strobe section 52 and a camera section 53 that are arranged on the side wall of the TP storage section 51.

The strobe section 52 is a cylindrical entrance-side light guide section 52.
1, a strobe 522 serving as a light source is disposed at one end thereof, and a slit plate 523 for blocking light emitted from the strobe 522 into a plurality of linear light rays described later is disposed at the other end thereof. In addition, the camera unit 52 includes the cylindrical exit-side light guide unit 5
It has a camera 532 that sets the film through 31.

Then, the photographing device 5 includes the output side light guide portion 531.
By operating a shutter 55 provided in the strobe 522, light is emitted from the strobe 522, the light is applied to the surface of the test piece 1 through a slit plate 523, and the light is reflected to be filmed by a camera 532. Has been done.

As shown in FIG. 2, the slit plate 523 is divided into 9 to 20 areas of 12 grades. Each area is provided with a slit so as to obtain a plurality of parallel light rays (slit light), and the interval of the slits is set to be narrower in an area having a higher score. In this example, the width dimension (thickness) of the slit S is uniformly set to 0.20 mm. The interval (pitch) of the slits S was set as shown in Table 2.

[0044]

[Table 2]

The tension meter was evaluated by using a photograph taken by the photographing device 5 with the sample to be evaluated placed on the mounting position of the test piece 1. Specifically, the plurality of slit lights shown in the photograph are visually observed for each area to determine whether or not the adjacent slit lights have an overlap. Then, the maximum score in the area where the slit light did not overlap was used as the evaluation value. This evaluation method is an evaluation method generally used by automobile manufacturers and the like.

Table 3 shows the results of these evaluations. In Table 3, ◯ means pass, and x means fail. Regarding the quality after coating, those having a tension meter evaluation value of 15 or more were accepted. In addition, as a vehicle body panel material for automobiles, dent resistance is required, and therefore a material having a proof stress of 110 MPa or more was accepted. Also, since workability in post-processing such as hemming is required, those with an elongation of 15% or more were accepted. Regarding the image clarity after coating (tension meter evaluation value), the one having an evaluation value of 15 or more was passed.

[0047]

[Table 3]

As can be seen from Table 3, the samples E11 to E16, which are the products of the present invention, passed the evaluations of proof stress, elongation and tension meter. On the other hand,
In Comparative Example C11, the yield strength was low because the amount of Mg added was small, and the crystal grain size during blow molding was large, so that the appearance was rough and the evaluation of the tension meter failed. In Comparative Example C12, since the amount of Mg added was too high,
It was not possible to evaluate because the plate was cracked during hot working. In Comparative Example C13, Mn and Cr were not added, and the crystal grain size during blow molding became large, so that the appearance was rough and the evaluation of the tension meter failed. Since Comparative Example C14 contained a large amount of Fe and Si, cavitation occurred during blow molding, and the elongation was unacceptable.

Example 2 In this example, Al-4.8% M
g-0.7% Mn-0.15% Cr-0.02% Si-
A slab having a composition of 0.02% Fe-0.01% Cu-50 ppm Be was manufactured by semi-continuous casting. This slab was homogenized by keeping it at a temperature of 500 ° C for 8 hours, then faced and heated to 395 ° C to make hot-rolled sheets. Was produced. Steps E21, E22, and E23 in Table 4 are the method of the present invention, and steps C21 to C30 are steps different from the present invention for comparison. Of these, steps E23, C29, and C30 are those in which the intermediate annealing before cold rolling in the batch furnace is performed after hot rolling.

[0050]

[Table 4]

Next, the obtained aluminum alloy plate having a thickness of 1.3 mm was cut into a square of 350 mm square to prepare a test piece, and hot blow molding was actually performed. In particular,
In the same manner as in Example 1, the test piece was heated to 490 ° C,
Hot blow molding was performed by a female mold into a rectangular tube shape of 250 mmW × 250 mmL × 65 mmH. The wall thickness of the central portion of the bottom surface was 0.85 mm, and the wall thickness reduction rate was about 34.6%.

Next, in the same manner as in Example 1, the mechanical properties of the central portion of the obtained rectangular tubular molded product were measured by a tensile test. Similarly, a 100 mm square test piece is cut out from the center, pickled, and then painted for general vehicles.
The quality (sharpness) of the coating film was evaluated with a tension meter.
The evaluation method with the tension meter is the same as in Example 1. In addition, in this example, in addition to the evaluation by the tension meter, the surface evaluation of the blow-molded product was performed by observing the appearance.
Specifically, Mg oxide on the plate surface after intermediate annealing before cold rolling
It was visually observed whether the mottled pattern caused by the presence of streaky stains extended in the subsequent rolling was observed, and when stains were observed, it was evaluated as ×, and when the surface was clean without stains, it was evaluated as ○. . Then, comprehensive evaluation was performed by combining the surface evaluation of this blow-molded product and the above-mentioned tension meter evaluation. The evaluation results are shown in Table 5. In Table 5, ◯ indicates pass, and x indicates fail.

[0053]

[Table 5]

As known from Table 5, steps E21 and E
The aluminum alloy sheet obtained in No. 22 was hot blow-molded, and a satisfactory appearance was obtained. On the other hand, in step C21, since the intermediate annealing was omitted,
The evaluation was inferior because the non-uniform structure of the hot rolled sheet could not be improved. Since the cold rolling rate before the intermediate annealing was low in the step C22, the uneven evaluation of the hot rolled sheet could not be improved without recrystallization due to the intermediate annealing, and the evaluation was poor. Process C2
In No. 3, the rolling ratio before the final annealing was too high, which resulted in the formation of a strong shear structure, and the structure after the final annealing became non-uniform and the evaluation was poor.

In steps C24 and C25, since the intermediate or final annealing temperature was too low, recrystallization did not take place, the nonuniform structure of the hot rolled sheet could not be improved, and the evaluation was poor. Process C2
No. 6, C27 was poor in evaluation because the recrystallization was non-uniformly generated because the temperature rising rate in the intermediate or final annealing was too low and the non-uniform structure of the hot-rolled sheet could not be improved. Process C2
In No. 8, the cold rolling ratio before the final annealing was low, so that recrystallization was not performed in the final annealing, the nonuniform structure of the rolled sheet could not be improved, and the evaluation was poor.

In step E23, the intermediate annealing before cold rolling was carried out as described above, and the load was small and the rolling could be easily performed in the subsequent cold rolling (cold rolling 1). The surface of the obtained blow molded product was beautiful and the surface quality was excellent.

On the other hand, in steps C29 and C30, although the intermediate annealing before cold rolling was performed, the heating temperature and the holding time thereof exceeded the range of the present invention (claim 2). In each case, the load of cold rolling (cold rolling 1) after the intermediate annealing before cold rolling was small and the rolling could be performed easily, but on the surface of the plate after the intermediate annealing before cold rolling, A mottled pattern due to Mg oxide was generated, and the surface quality was inferior.

(Example 3) In this example, Al-4.8% M
g-0.7% Mn-0.15% Cr-0.02% Si-
A slab having a composition of 0.02% Fe-0.01% Cu-50 ppm Be was manufactured by semi-continuous casting. This slab was subjected to a homogenization treatment in which it was kept at a temperature of 500 ° C. for 8 hours, after being faced, heated to 395 ° C. and hot-rolled. Next, for the obtained hot-rolled sheet, cold rolling (cold rolling rate 50%) → intermediate annealing (heating rate 10 ° C./sec, holding temperature 500 ° C.,
Holding time 30 seconds → cold rolling (cold rolling rate 33%) → final annealing (heating rate 10 ° C / sec, holding temperature 500 ° C,
The holding time of 30 seconds) was sequentially applied to obtain an aluminum alloy plate as an intermediate material.

Then, in this example, as shown in Table 6, the aluminum alloy plate as the intermediate material was further subjected to cold rolling and finish heat treatment, and the effect thereof was evaluated.
The final plate thickness is 1.3 mm regardless of which process is selected.
The thickness of the hot rolled plate was adjusted so that As the cold rolling after the final annealing, in addition to the step E31 in which the cold rolling rate is 33%, the cold rolling rate is 5% and 65%.
The comparative steps C31 and C32 changed to the above were also performed. In addition, in any of the processes, the finish heat treatment is performed at a temperature rising rate of 10
C./sec, holding temperature of 350.degree. C., holding time of 5 seconds.

[0060]

[Table 6]

Next, the obtained aluminum alloy plate was
A test piece was cut out into a square shape of 0 mm square. In this example, first, the test piece was subjected to cold working after bending R3 and then bending back. Then, in the same manner as in Example 1, the test piece was heated to 490 ° C., and 250 mmW ×
Hot blow molding was performed by a female mold into a rectangular tube shape of 250 mmL × 65 mmH. Next, a 100 mm square test piece was cut out from the center of the obtained square tube molded product, and after pickling,
We carried out coating for general automobiles and evaluated the quality (sharpness) of the coating film with a tension meter. The evaluation method is the same as in Example 1. The evaluation results are shown in Table 7.

[0062]

[Table 7]

The product of step E31 had a good appearance. Regarding step C31, a ridge-like defect was generated along the fold line that was bent-bent back. In addition, since the degree of cold working was low, uneven recrystallization (coarsening) occurred during heating to the hot blow molding temperature in the portion subjected to bending, so it was judged that evaluation was not possible. In step C32, the rolling ratio before heat treatment was too high, which resulted in the formation of a strong shear structure.
Poor evaluation due to non-uniform recrystallization along shear during heating to hot blow molding temperature.

From the results of this example, as an aluminum alloy sheet used for cold working before hot blow molding, a cold rolling ratio of at least 25% or more and less than 50% was obtained after the final annealing. It can be seen that it is effective to carry out cold rolling in the following manner, and then to carry out a finish heat treatment of heating within a temperature range of 270 ° C to 400 ° C at a heating rate of 1 ° C / sec or more and holding for 5 minutes or less. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an imaging device for measuring a tension meter according to a first embodiment.

FIG. 2 is an explanatory diagram showing a slit arrangement of a slit plate in the first embodiment.

[Explanation of symbols]

1. ． ． Test piece, 5. ． ． Imaging device, 50. ． ． Base 50, 51. ． ． TP storage, 52. ． ． Strobe part, 53. ． ． Camera unit 53,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C22F 1/00 623 C22F 1/00 623 682 682 683 683 683 684 684C 685 685Z 686 686B 691 691A 691B 691C 694A (72) Mineo Asano Mineo Asano 5-11-3 Shimbashi, Minato-ku, Tokyo Within Sumitomo Light Metal Industry Co., Ltd. (72) Inventor Yokoyama Zhen 1-10 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. In-house (72) Inventor Hiroshi Ochiai 1-10-1, Shin-Sayama, Sayama-shi, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Shintaku Yasunaga 1-1-4-1 Chuo, Wako, Saitama Stock Company Honda Giken In-house (72) Inventor Toshiya Nishino Saitama Light Chuo 1-chome No. 4 No. 1 stock company Honda Motor in the Institute

Claims (12)

[Claims] 1. A weight ratio of Mg: 3.5 to 6.0.
%, And one or two of Mn: 0.5 to 0.8% or Cr: 0.05 to 0.20%, and a Si content of 0.10% or less, Fe content is regulated to 0.12% or less, Cu content is regulated to 0.10% or less, and the balance is made of an alloy consisting of Al and unavoidable impurities. The ingot is hot-rolled after homogenization treatment and further cooled. Cold rolling with a cold rolling rate of 25% or more was performed, and the temperature rising rate was 1 ° C / s.
ec or more, intermediate annealing is performed by heating within a temperature range of 400 ° C to 550 ° C and holding for 5 minutes or less, and after the intermediate annealing, cold rolling is performed at a cold rolling rate of 25% or more and less than 50% up to the final plate thickness. Rolled, then 400 at a heating rate of 1 ° C / sec or more
An Al-Mg-based aluminum alloy plate for hot blow molding, characterized by being subjected to final annealing for heating within a temperature range of 550 to 550 ° C and holding for 5 minutes or less. 2. The intermediate annealing before cold rolling according to claim 1, wherein after the hot rolling is performed, it is heated in a temperature range of 300 ° C. to 500 ° C. in a batch furnace and held for 1 hour to 10 hours. A for hot blow molding characterized by applying
1-Mg-based aluminum alloy plate. 3. The alloy according to claim 1 or 2,
Furthermore, Be: 20-80 ppm is contained, The Al-Mg type aluminum alloy plate for hot blow molding characterized by the above-mentioned. 4. The method according to claim 1, wherein
After performing the above-mentioned final annealing, cold rolling is further performed at a cold rolling rate of 25% or more and less than 50%, and then the temperature rising rate 1
An Al-Mg-based aluminum alloy plate for hot blow molding, which has been subjected to a finishing heat treatment of heating within a temperature range of 270 ° C. to 400 ° C. at a temperature of ≧ ° C./sec and holding for 5 minutes or less. 5. The method according to any one of claims 1 to 4,
An Al-Mg based aluminum alloy plate for hot blow molding, wherein the plate material is a vehicle body panel material for automobiles. 6. A hot-blow-molded product obtained by hot-blow-molding an aluminum alloy plate in a temperature range of 400 ° C. or higher, wherein the aluminum alloy plate has a weight ratio of Mg: 3.5-6. 0.0% and Mn:
0.5-0.8%, or Cr: 0.05-0.20
%, 1 type or 2 types are contained, Si content is 0.10% or less, Fe content is 0.12% or less, Cu content is 0.10% or less, and the balance is Al and unavoidable. Made of an alloy of mechanical impurities, the ingot is hot-rolled after the homogenization treatment, and further cold-rolled at a cold rolling rate of 25% or more, and at a temperature rising rate of 1 ° C / sec or more, 400 ° C to 5 ° C.
Intermediate annealing is performed by heating within a temperature range of 50 ° C and holding for 5 minutes or less, and after the intermediate annealing, the final plate thickness is 25% or more 5% or more.
Cold rolling is performed at a cold rolling rate of less than 0%, and then a final annealing is performed in which the temperature is raised within a temperature range of 400 ° C to 550 ° C at a temperature rising rate of 1 ° C / sec or more and held for 5 minutes or less. A hot-blow molded article, which is an Al-Mg-based aluminum alloy plate for hot-blow molding described above. 7. The intermediate annealing before cold rolling according to claim 6, wherein after the hot rolling is performed, it is heated in a temperature range of 300 ° C. to 500 ° C. in a batch furnace and held for 1 hour to 10 hours. Hot blow molded product characterized by being subjected to. 8. The method according to claim 6 or 7, wherein after the final annealing, cold rolling is further performed at a cold rolling rate of 25% or more and less than 50%, and then at a temperature rising rate of 1 ° C./sec or more. A hot blow-molded article, which has been subjected to a finishing heat treatment for heating within a temperature range of 270 ° C to 400 ° C and holding for 5 minutes or less. 9. A hot blow-molded product obtained by subjecting an aluminum alloy plate to cold plastic working and then hot blow molding in a temperature range of 400 ° C. or higher, wherein the aluminum alloy plate has a weight ratio of In, Mg: 3.5-6.0%
And Mn: 0.5-0.8%, or C
r: One or two of 0.05 to 0.20%, Si content of 0.10% or less, Fe content of 0.12% or less, Cu content of 0.10% or less Regulated by the regulations, the balance consisting of alloy consisting of Al and inevitable impurities, the ingot is subjected to homogenization treatment, hot rolling, cold rolling with a cold rolling rate of 25% or more, and a heating rate of 1 ° C. / S
ec or more, intermediate annealing is performed by heating within a temperature range of 400 ° C to 550 ° C and holding for 5 minutes or less, and after the intermediate annealing, cold rolling is performed at a cold rolling rate of 25% or more and less than 50% up to the final plate thickness. Rolled, then 400 at a heating rate of 1 ° C / sec or more
The final annealing is carried out by heating within the temperature range of ℃ to 550 ℃ and holding for 5 minutes or less, and further cold rolling is performed at a cold rolling rate of 25% or more and less than 50%, and then the temperature rising rate is 1 ℃. / S
A hot-blown Al-Mg-based aluminum alloy plate for hot-blow molding, which has been subjected to a finish heat treatment for heating within a temperature range of 270 ° C to 400 ° C at ec or more and holding for 5 minutes or less. Molding. 10. The intermediate annealing before cold rolling according to claim 9, wherein after the hot rolling is performed, it is heated in a temperature range of 300 ° C. to 500 ° C. in a batch furnace and held for 1 hour to 10 hours. Hot blow molded product characterized by being subjected to. 11. A hot blow-molded article according to claim 6, wherein the alloy further contains Be: 20 to 80 ppm. 12. The hot blow molded product according to any one of claims 6 to 11, wherein the hot blow molded product is an automobile body panel.