JP2001020027A - Al-Mg-Si-Cu ALLOY SHEET EXCELLENT IN CORROSION RESISTANCE AND FORMABILITY, AND ITS MANUFACTURE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an Al-Mg-Si-Cu alloy sheet having high BH characteristic and excellent in corrosion resistance as well as in formability. SOLUTION: This alloy has a composition consisting of, by weight, 0.1-0.65% Mg, 0.4-2% Si, 0.8-1.4% Cu, further one or plural kinds among 0.03-1.5% Zn, 0.03-0.2% Mn, 0.03-0.2% Cr, 0.03-0.15% Zr, 0.03-0.15% V, 0.03-0.3% Fe, and 0.005-0.1% Ti, and the balance Al with inevitable impurities and satisfying Mg+Cu=0.9 to 1.5. Moreover, the maximum size of Cu-containing precipitates on the grain boundaries is <=0.5μm and these precipitates comprise <=5% of the grain boundary surface, and further, the number of crystallized substances of >=0.2μm maximum size in the grain is <20 pieces to 100 μm2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al-Mg-Si-Cu alloy plate for forming and used as a material for body sheets and parts of automobiles, various machine tools, home electric parts and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Applications requiring high moldability and high strength,
For example, cold rolled steel sheets are mainly used for body sheets of automobiles, but weight reduction is required from the viewpoint of improving fuel efficiency, and aluminum alloy sheets are being used. Since the formability by press working is required for this automobile body sheet, 5000 series which is excellent in strength and formability among aluminum alloys, that is, Al-Mg alloy is used. However, Al-Mg alloys have a high cost due to poor manufacturability, and are liable to generate Rudersmark, so that it is difficult to obtain good surface properties after molding. Therefore, it is desirable to use the 6000 series, which has a low production cost and does not generate Ruder's mark, that is, Al-Mg-Si, and therefore, development is proceeding.

[0003]

However, Al-Mg-
The formability of the Si-based alloy is inferior to that of the Al-Mg-based alloy. This is an alloy in which an Al-Mg-Si-based alloy can obtain high strength by precipitation strengthening. The strength is increased after baking, so-called BH property is excellent, but a precipitate is easily generated at the time of production, and ductility is caused by the precipitate. Is to be reduced. Further, a study of manufacturing conditions such as a heat treatment condition has been prioritized with a focus on enhancing the BH property for securing the strength (for example, JP-A-4-259358 and JP-A-6-259358). 204259), the study of moldability is insufficient.

[0004] To solve this problem, there is a method of improving the formability by adding Cu. However, although the moldability is improved by the addition of Cu, the corrosion resistance is deteriorated. Therefore, when used for an automobile body sheet, the rust resistance is particularly problematic. The present invention improves the formability by adding Cu to an Al-Mg-Si system, and further prevents Al-Mg-Si-C having a high BH property from preventing a decrease in corrosion resistance due to the addition of Cu.
It provides a u-based alloy.

[0005]

The present inventors have conducted detailed studies in order to solve the above-mentioned problems, and have clarified that the decrease in corrosion resistance due to the addition of Cu is caused by Cu-based precipitates generated at crystal grain boundaries. It has been found that by controlling the precipitates, it is possible to achieve both BH property, formability and corrosion resistance. Furthermore, the size and the state of the Cu-based precipitates are controlled by limiting the component systems, particularly the amounts of Mg and Cu, and more preferably by limiting the lower limit of the cooling rate after the solution treatment, particularly the production conditions, and Al-Mg-Si-Cu based alloys having excellent BH properties and excellent corrosion resistance have been invented.

That is, the gist of the present invention is as follows: (1) Mg: 0.1 to 0.65%, Si:
0.4-2%, Cu: 0.8-1.4%, Mg + Cu:
0.9-1.5%, Zn: 0.03-1.5
%, Mn: 0.03 to 0.2%, Cr: 0.03 to 0.
2%, Zr: 0.03 to 0.15%, V: 0.03 to
0.15%, Fe: 0.03 to 0.3%, Ti: 0.0
The maximum diameter of a Cu-containing precipitate on a crystal grain boundary, which further contains one or more of 0.05 to 0.1%, and the balance is an Al alloy including Al and unavoidable impurities. Is 0.5 μm or less, and the proportion occupying the crystal grain interface is 5% or less, and crystal precipitates having a maximum diameter of 0.2 μm or more in the grains are 20 μm / 100 μm ^2.
An Al-Mg-Si-Cu-based alloy plate excellent in corrosion resistance and formability, characterized in that the number is less than one.

(2) Al-Mg-S as described in (1) above
A method for producing an i-Cu alloy sheet, wherein a solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and a cooling rate after the solution treatment is a cooling rate in a temperature range from a solution treatment temperature to 200 ° C. 1
A method for producing an Al-Mg-Si-Cu alloy sheet excellent in corrosion resistance and formability, characterized in that the temperature is higher than 5 ° C / sec. (3) The method for producing an Al-Mg-Si-Cu-based alloy sheet according to (1), wherein after hot rolling, the temperature is 250 ° C or higher.
A method for producing an Al-Mg-Si-Cu-based alloy sheet, wherein the sheet is held at a temperature lower than 50C for 0.5 to 4 hours.

(4) Al-Mg-S as described in (1) above
A method for producing an i-Cu alloy sheet, wherein a solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and a cooling rate after the solution treatment is a cooling rate in a temperature range from a solution treatment temperature to 200 ° C. 1
After 5 ° C / sec or more and winding at 40 to 100 ° C,
Al-Mg-Si-C excellent in corrosion resistance and formability characterized by cooling at a cooling rate of 0.1 to 10 ° C / h.
A method for producing a u-based alloy plate. (5) The method for producing an Al-Mg-Si-Cu alloy sheet according to (1), wherein the solution treatment after the cold rolling is performed by 5
The cooling after the solution treatment is performed at a cooling rate of 15 ° C./sec in the temperature range from the solution temperature to 200 ° C.
After super winding and winding at 40-100 ° C, 40-100 ° C
The method for producing an Al-Mg-Si-Cu alloy sheet excellent in corrosion resistance and formability, characterized by holding for 0.5 to 50 hours.

(6) Al-Mg-S as described in (1) above
A method for producing an i-Cu alloy sheet, wherein a solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and a cooling rate after the solution treatment is a cooling rate in a temperature range from a solution treatment temperature to 200 ° C. 1
After 5 ° C / sec or more and winding at 40 to 100 ° C,
Cool at a cooling rate of 0.1 to 10 ° C / h, and further cool
Al-Mg-Si- excellent in corrosion resistance and moldability characterized in that it is heated to -280 ° C and held for more than 0 to 30 minutes.
A method for producing a Cu-based alloy plate. (7) The method for producing an Al-Mg-Si-Cu alloy plate according to (1), wherein the solution treatment after the cold rolling is performed by 5
The cooling after the solution treatment is performed at a cooling rate of 15 ° C./sec in the temperature range from the solution temperature to 200 ° C.
After super winding and winding at 40-100 ° C, 0.1-10 ° C
/ H, cooling to 130-280 ° C and keeping for more than 0-30 minutes, then cooling to 40-100 ° C and winding, cooling rate of 0.1-10 ° C / h Al- with excellent corrosion resistance and moldability characterized by cooling with
A method for producing an Mg—Si—Cu alloy plate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The reasons for limiting the alloy composition, the precipitation state of precipitates, the production conditions and the like according to the present invention will be specifically described below. Mg: Mg is a basic alloying element in the alloy system of the present invention, and contributes to the manifestation of high BH properties by generating Mg-Si based fine precipitates during baking. But,
When the amount of Mg is less than 0.1%, the BH property is not insufficient. On the other hand, an excessive addition exceeding 0.65% produces coarse Mg-Si-Cu-based precipitates at the crystal grain boundaries, resulting in corrosion resistance and formability. Lower. From this, the amount of Mg is 0.1 to
The range is 0.65%.

Si: Si is also a basic alloying element in the alloy system of the present invention, and contributes to the development of high BH property by generating Mg-Si based fine precipitates during baking.
When the amount is less than 0.4%, the BH property is insufficient.
%, A coarse Si phase is precipitated to lower the formability. For this reason, the amount of Si is set in the range of 0.4 to 2%.

[0012] Cu: Cu is also a basic alloying element in the alloy system of the present invention, and improves the formability. However, if the Cu content is less than 0.8%, sufficient formability cannot be ensured.
Coarse A at the grain boundaries due to excessive addition exceeding 1.4%
1-Mg-Si-Cu-based precipitates are formed, and the corrosion resistance and the formability are reduced. From this, the Cu content is 0.8 to
It is in the range of 1.4%. Furthermore, 0.9% of Mg + Cu
If it is less than 1.5%, the BH property and moldability are insufficient, and
Is exceeded, the Al-Mg-Si under normal solution treatment conditions
-Since the formation of Cu-based precipitates cannot be suppressed and the corrosion resistance and moldability are reduced, Mg + Cu is reduced to 0.9 to 0.9%.
The range is 1.5%.

Zn, Mn, Cr, Zr, V, Ti, F
e: These elements are used for improving strength and refining crystal grains.
Seeds or two or more are added. Of these, Zn is an element that contributes to the strength improvement through the improvement of the aging property of the alloy. If its content is less than 0.03%, the above-mentioned effects are insufficient, while if it exceeds 1.5%, Moldability and corrosion resistance decrease. Therefore, when Zn is added, the amount of Zn is set in the range of 0.03 to 1.5%.

Further, Mn, Cr, Zr, and V are elements that are effective in improving the strength and refining the crystal grains. If the content is less than 0.03%, the above effects cannot be sufficiently obtained. On the other hand, Mn and Cr are 0.2% and Zr is 0.15%.
When V exceeds 0.1%, a large intermetallic compound is formed to lower the moldability. Therefore, Mn is 0.03 to
0.2%, Cr is 0.03-0.2%, Zr is 0.03
Ｖ0.15%, and V was in the range of 0.03〜0.15%.

Further, Fe is also an element effective for improving the strength and refining the ingot structure. If its content is less than 0.03%, a sufficient effect cannot be obtained. The amount of Fe is 0.03-
0.3%. Ti is also an element effective for improving the strength and refining the ingot structure. If the content is less than 0.005%, a sufficient effect cannot be obtained. If the content exceeds 0.1%, a giant crystal is generated. To reduce the formability, the Ti content is 0.005.
To 0.1%. In addition, these Zn, Mn, Cr,
The ranges of Zr, V, Fe, and Ti show the cases where these elements are included as positively added elements, and it is not particularly hindered to include any of the elements in an amount smaller than the lower limit as an impurity.

Next, C deposited on the alloy sheet in the present invention
The size and the state of precipitation of the u-based precipitate will be described. Precipitates that affect formability and corrosion resistance depend on the size, location and distribution of the precipitates. That is, if the Cu-based precipitate is on the crystal grain boundary and the maximum diameter is 0.5 μm or more, or the maximum diameter is 0.5 μm.
If the ratio occupying the crystal grain boundary exceeds 5% even if it is less than m, cracks are likely to occur along the crystal grain boundary, and the formability decreases. In addition, if Cu-based precipitates are formed in the above-mentioned distribution state on the crystal grain boundaries, the amount of Cu around the precipitates is reduced, so that intergranular corrosion, that is, thread rust, is likely to occur.

When the crystal precipitate is in the crystal grain,
When 20 or more precipitates having a maximum diameter of 0.2 μm or more can be detected in 100 μm ² , the number of starting points of fracture increases, and the formability decreases. Therefore, the crystal precipitation state of the crystal precipitate of the cold rolled sheet is specified as described above. In addition, the precipitation state of the Cu-based precipitates in the crystal grain boundaries and the crystal precipitates in the crystal grains can be determined by photographing any five visual fields at a magnification of about 5000 times using a transmission electron microscope and observing the size from the photograph. can do.

Further, production conditions for securing the above-mentioned precipitate will be described. The steps up to the production of the hot rolled sheet may be the same as those of a conventional general JIS 6000 series alloy. That is, the method comprises a step of forming an ingot by a method such as DC casting or continuous casting, performing homogenization treatment, performing surface grinding as necessary, and subsequently performing hot rolling, cold rolling, and solution treatment. . When the solution temperature is lower than 520 ° C., the added element does not form a solid solution sufficiently, and a Cu-based precipitate having a maximum diameter of 0.5 μm or more precipitates at the crystal grain boundary. % Or a precipitate having a maximum diameter of 0.2 μm or more in a crystal grain.
20 or more can be detected within 00 μm ² , which is not preferable. Further, such a solution treatment is generally performed in a continuous annealing furnace, and if the treatment time exceeds 5 minutes, it means that the sheet passing speed is reduced, and the productivity is significantly reduced. Therefore, the solution treatment time is set to 5 minutes or less.

Further, the solution temperature is set at 20% from the solution temperature after the solution treatment.
The cooling rate to 0 ° C. needs to be higher than 15 ° C./sec in order to suppress precipitation during cooling. If it is slower than this, C having a maximum diameter of 0.5 μm or more is
u-based precipitates are precipitated, or the proportion of the precipitates occupying the crystal grain boundary exceeds 5%, or precipitates having a maximum diameter of 0.2 μm or more in crystal grains are contained in 100 μm ² .
This is not preferable because more than one can be detected. Therefore, the cooling rate after the solution treatment is set to a cooling rate of more than 15 ° C./sec in a temperature range from the solution treatment temperature to 200 ° C. After the solution treatment, it is effective to immediately perform stabilization treatment at about 100 ° C. for several hours in order to suppress aging at room temperature and obtain high BH property.

Further, intermediate annealing before or during cold rolling is also effective as a method for controlling the precipitation state of precipitates. That is, this is a method of controlling precipitation during cooling after solution treatment by generating Cu-based precipitates by intermediate annealing and suppressing re-dissolution of precipitates during solution treatment. If the heat treatment conditions at this time are lower than 250 ° C., the effect of suppressing the grain boundary precipitation of fine precipitates is small,
If the temperature is higher than 50 ° C., coarse precipitates are formed and cannot be solid-dissolved again during the solution treatment. Therefore, a sufficient supersaturated solid solution cannot be obtained, and as a result, moldability and BH property are reduced.

Further, even when annealing at a temperature of 250 ° C. or more and 450 ° C. or less, if the annealing time is less than 0.5 hour, the effect of suppressing grain boundary precipitation during cooling after the solution treatment is small. On the other hand, if it exceeds 4 hours, coarse precipitates are formed and cannot be dissolved again during the solution treatment, so that a sufficient supersaturated solid solution cannot be obtained. As a result, moldability and B
Reduces H properties. Therefore, the heat treatment condition is set to 250 ° C.
The temperature is set to be not less than 450 ° C. and not more than 0.5 hours and not more than 4 hours.
By controlling the precipitates precipitated on the crystal grain boundaries by performing the above heat treatment, it becomes possible to relax the conditions for the solution treatment after cold rolling.

Further, by controlling the winding temperature after the solution treatment and the cooling rate after the winding, the BH property can be improved. If left near room temperature after the solution treatment, the amount of clusters generated will increase.
Since the precipitation of the P zone is prevented, the BH property is reduced. To prevent this, wind at a temperature of 40 ° C or higher, and
It is effective to generate a P zone. However, if the winding temperature exceeds 100 ° C., the increase in proof stress due to the generation of the GP zone is large, and the formability decreases. In addition, it is necessary to sufficiently generate a GP zone during cooling after winding, and to suppress a decrease in BH properties.
If it exceeds 0 ° C./h, this effect is insufficient. Conversely, if the cooling rate is too slow and is less than 0.1 ° C./h, the increase in proof stress due to the generation of the GP zone is large, impairing the formability.
Therefore, the winding temperature is set in the range of 40 to 100 ° C, and the cooling rate after winding is set in the range of 0.1 to 10 ° C / h.

Further, after winding under the above-mentioned conditions, instead of cooling to room temperature by controlling the cooling rate, heat treatment is performed in a temperature range in which a GP zone is quickly generated.
BH property can be improved. If the heat treatment temperature is lower than 40 ° C., a large number of clusters are formed to inhibit the BH property. If the heat treatment temperature is higher than 100 ° C., the yield strength increases and the formability decreases. If the time is less than 0.5 hour, the formation of the GP zone is insufficient, so that if left at room temperature thereafter, clusters are formed and the BH property is reduced. Flexibility decreases. Therefore, the heat treatment temperature is in the range of 40 to 100 ° C., and the heat treatment time is in the range of 0.5 to 50 hours.

In order to obtain a higher BH property, it is effective to perform a rewinding treatment at a relatively high temperature and for a short time after winding, cooling or heat treatment under the above conditions after the solution treatment. That is, the generation of the GP zone after the solution treatment suppresses the generation of the cluster, and further, the cluster is dissolved by the restoring treatment to generate the GP zone, whereby an extremely high BH property is obtained. Also in this case, the winding temperature after the solution treatment is set to the lower limit when the temperature is lower than 40 ° C. because clusters are formed, and is set to the upper limit when the temperature is higher than 100 ° C. because the yield strength increases and the formability and bendability decrease.
If the cooling rate is less than 0.1 ° C./h, the yield strength is increased and the formability and bendability are reduced.
When h is exceeded, the generation of the GP zone is insufficient, and when left at room temperature thereafter, clusters are formed and the BH property is reduced, so the upper limit is set.

It is to be noted that the same effect can be obtained by cooling and winding after the solution treatment, and immediately performing a heat treatment at 40 to 100 ° C. for 0.5 to 50 hours. The restoring process is 13
If the temperature is lower than 0 ° C., the cluster does not dissolve and the GP zone is precipitated, so that the yield strength increases and the formability and bendability are impaired. On the other hand, when the temperature exceeds 280 ° C., the proof stress increases, and an intermediate phase is formed, so that the formability and the bendability are remarkably reduced. On the other hand, if the holding time exceeds 30 minutes, the proof stress increases, and the formability and the bendability decrease. Therefore, the temperature range of the restoration process is 130 to 280 ° C., and the holding time is more than 0 to 30 minutes.

In order to further improve the BH property, it is effective to perform winding and cooling under conditions that generate GP zones after the restoration processing. That is, if the precipitation of clusters after the restoration treatment is suppressed, a decrease in BH property can be prevented. In particular, when the restoration process is performed at a high temperature of 200 ° C. or more,
The dissolution of the clusters is promoted to increase the degree of supersaturation of the solute, and if left near room temperature after cooling, the clusters are formed again and the BH property tends to decrease. To prevent this,
As in the case after the solution treatment, the range of the winding temperature is set to 40 to 100.
The cooling rate range is 0.1 to 10 ° C / h. After the restoration treatment, the temperature is set to 40 to 100 ° C. in the same manner as after the solution treatment.
The same effect can be obtained by performing a heat treatment in which the film is wound at a temperature in the range described above and held at 40 to 100 ° C. for 0.5 to 50 hours.

[0027]

Next, the present invention will be specifically described based on examples. (Example 1) Each of the aluminum alloys shown in Table 1 was cast by a DC casting method according to a conventional method, and the obtained ingot was subjected to a homogenization treatment at 530 ° C for 5 hours, and then subjected to hot rolling. It was a rolled sheet. Next, after performing an intermediate annealing at 520 ° C. × 1 min, a cold-rolled sheet having a thickness of 1 mm was manufactured.
A solution treatment at 0 ° C. × 10 sec was performed. 54 at this time
The cooling rate between 0 ° C and 200 ° C was 18 ° C / sec.
Further, immediately after the solution treatment, a stabilization treatment at 100 ° C. × 3 hr was performed.

[0028]

[Table 1]

The precipitation state of the cold-rolled sheet manufactured under the above manufacturing conditions was photographed by a transmission electron microscope at a magnification of 5000 at five arbitrary fields, and the size and size of the precipitate observed in the range were measured. The number was measured and evaluated. Among the mechanical properties, a tensile test was performed by cutting out JIS No. 5 test pieces from these alloy plates and performing a tensile speed of 1 mm / min until the proof stress measurement, and a 10 mm / min tensile speed after the proof stress measurement. Also,
The BH property was evaluated by subjecting a tensile test piece to heat treatment at 180 ° C. for 20 minutes and measuring the proof stress.

For press formability evaluation, bending and overhanging were performed. First, in the bending test, a JIS No. 3 test piece was cut out, bent 180 ° at an inner radius of 0.5 t, and the outer part was observed for appearance. Those were evaluated as x. The overhanging formability was determined by using a 100 mm ball-overhanging tool, applying a lubricating oil to a test piece having a length of 200 mm and a width of 125 to 140 mm, and forming at a molding speed of 10 mm / min.
10 tons to form and determine the break forming height (LDH0)
evaluated.

The corrosion resistance was evaluated by putting artificial flaws with a knife on the sample surface which had been degreased, washed with water, treated with zinc phosphate, washed with water, and painted, sprayed with salt water and wetted, and evaluated for rust resistance. The evaluation of the yarn rust property was based on the maximum length of the yarn rust, and the evaluation was as follows. Table 2 shows the results of measurement of the state of the precipitate, mechanical properties, moldability, and corrosion resistance. The alloys of A1 to A12 shown in the present invention have a small proportion occupying the grain boundaries in a precipitation state within a specified range, have excellent elongation and bendability, have high formability with a high breaking limit height, and have a high B
It has H property.

[0032]

[Table 2]

On the other hand, among the alloys shown in the comparative examples, B1 has a small amount of Mg, B4 has a small amount of Si, so the BH property is insufficient, B2 has a large amount of Mg, and B5 has a large amount of Cu. Therefore, a Cu-based precipitate is generated at the crystal grain boundary, and the formability and the corrosion resistance are reduced. B3 has a large amount of Si and therefore has low formability, and B6 has a low Cu amount and therefore has insufficient formability. Further, other alloys shown in the comparative example,
The components that generate crystal precipitates are out of the range specified in the present invention, and the distribution of crystal precipitates in the grains is defined in the present invention even though the production conditions are manufactured within the range specified in the present invention. And, as a result, the bendability and formability are significantly inferior to those of the present invention.

Example 2 A manufactured in the same manner as in Example 1
Table 3 was obtained by using an alloy hot-rolled sheet within the range specified in the present invention of No. 4
The steel sheet was subjected to intermediate annealing under the following conditions to produce a cold-rolled sheet having a thickness of 1 mm. These cold-rolled sheets were subjected to the solution treatment shown in the table, and the precipitation state was observed in the same manner as in Example 1. The mechanical properties, press formability, and corrosion resistance were evaluated. As shown in the table, in the present invention, by performing the solution treatment under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, and as a result, the precipitate has excellent elongation and bendability, and has high formability. Thus, an alloy plate excellent in BH property and corrosion resistance was obtained.

[0035]

[Table 3]

[0036]

[Table 4]

On the other hand, of the comparative examples, In the case of No. 30, the solution treatment temperature is lower than the temperature specified in the present invention, a large number of coarse precipitates are observed at the grain boundaries, and the elongation and the formability are reduced. Also, among the comparative examples, No. In the case of 31, the cooling rate after the solution treatment is lower than the condition specified in the present invention,
It is considered that precipitates were precipitated at the grain boundaries during cooling and coarsened,
Many precipitates are observed at the grain boundaries, and elongation, formability and corrosion resistance are reduced.

Example 3 A produced in the same manner as in Example 1
Table 5 was obtained by using an alloy hot-rolled sheet within the range specified in the present invention of No. 4
The steel sheet was subjected to intermediate annealing under the following conditions to produce a cold-rolled sheet having a thickness of 1 mm. These cold-rolled sheets were subjected to a solution treatment shown in Table 5 and the precipitation state was observed in the same manner as in Example 1. The mechanical properties, press formability and corrosion resistance were evaluated. Table 6
As shown in the present invention, by performing the intermediate annealing conditions under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, as a result, excellent in elongation and bendability, having high formability and An alloy plate having excellent BH properties and corrosion resistance was obtained.

[0039]

[Table 5]

[0040]

[Table 6]

On the other hand, among the comparative examples, No. 37 and N
o. In the case of No. 38, since the intermediate annealing temperature was lower than the temperature specified in the present invention or the time was short, the precipitate did not sufficiently coarsen during the intermediate annealing, so that a fine precipitate was formed after the solution treatment, and the elongation was increased. It is considered that moldability and corrosion resistance were reduced. In addition, No. 39 and no. In No. 40, since the intermediate annealing time was too long, the precipitates were coarsened, re-solid solution by the solution treatment was insufficient, and a large number of coarse precipitates were observed at the grain boundaries, and elongation and formability were reduced. In addition, No. In the case of 41, most of the crystal precipitates re-dissolved during the intermediate annealing because the intermediate annealing temperature was too high, and under the condition of low solution treatment temperature, the precipitation was promoted, and the precipitates were precipitated at the grain boundaries. It is considered to be coarse, and a large number of precipitates were observed at the grain boundaries, and elongation, formability and corrosion resistance were reduced.

(Example 4)
Table 3N shows the hot-rolled alloy sheets within the range specified in the present invention of A4.
o. No. 27 was subjected to intermediate annealing to produce a cold-rolled sheet having a thickness of 1 mm. A solution treatment shown in FIG. 27 was performed. Further, after winding under the conditions shown in Table 7 and cooling to near room temperature, the precipitation state of these alloy sheets was observed, and the mechanical properties, press formability, and corrosion resistance were evaluated in the same manner as in Example 1. It was shown to. As shown in Table 8, in the present invention, by performing the solution treatment under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, and as a result, the precipitate has excellent elongation and bendability, and high formability is obtained. An alloy plate having excellent BH properties and corrosion resistance was obtained.

[0043]

[Table 7]

[0044]

[Table 8]

On the other hand, among the comparative examples, No. In the case of No. 46, since the winding temperature was lower than the temperature specified in the present invention, clusters were formed during cooling and the BH property was lowered. On the other hand, No.
In the case of No. 47, since the winding temperature was higher than the temperature specified in the present invention, a GP zone was generated during cooling, the proof stress increased, and the bendability decreased. In addition, No. In the case of No. 48, since the cooling rate after winding was too high, the precipitation of the GP zone during cooling was insufficient and clusters were formed, and the BH property was lowered.
On the other hand, No. In the case of 49, since the cooling rate after winding is too slow, a GP zone is generated during cooling, the proof stress increases, and the bendability decreases.

(Example 5)
Table 3N shows the hot-rolled alloy sheets within the range specified in the present invention of A4.
o. No. 27 was subjected to intermediate annealing to produce a cold-rolled sheet having a thickness of 1 mm. A solution treatment shown in FIG. 27 was performed. Further, it was wound up under the conditions shown in Table 9 and immediately subjected to heat treatment. The precipitation state of these alloy sheets was observed, and the mechanical properties, press formability and corrosion resistance were evaluated in the same manner as in Example 1. Indicated. As shown in Table 10, in the present invention, by performing the solution treatment under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, and as a result, the elongation and bendability are excellent, and the high formability is improved. An alloy plate having excellent BH properties and corrosion resistance was obtained.

[0047]

[Table 9]

[0048]

[Table 10]

On the other hand, among the comparative examples, no. In the case of No. 54, since the heat treatment temperature was lower than the temperature specified in the present invention, clusters were generated and the BH property was reduced. In the case of No. 55, since the heat treatment temperature was higher than the temperature specified in the present invention, a GP zone was generated, the proof stress increased, and the bendability decreased. Also, N
o. In the case of No. 56, since the heat treatment time was short, the precipitation of the GP zone was insufficient, clusters were formed, and the BH property was lowered. On the other hand, No. In the case of No. 57, since the heat treatment time is too long, a GP zone is generated, the proof stress increases, and the bendability decreases.

Example 6 A manufactured in the same manner as in Example 1
No. 4 in Table 3 No. 4 was added to the hot-rolled alloy sheet within the range specified in the present invention.
Intermediate annealing under the conditions shown in No. 27 was performed to produce a cold-rolled sheet having a thickness of 1 mm. Further, Table 3 No. After performing the solution treatment shown in Table 27, the film was wound under the conditions shown in Table 7 production number 42, cooled to near room temperature, and subjected to a restoration treatment shown in Table 11. Thereafter, the precipitation state was observed in the same manner as in Example 1, and the mechanical properties, press formability, and corrosion resistance were evaluated.
It was shown to. As shown in the table, in the present invention, by performing the solution treatment under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, and as a result, the precipitate has excellent elongation and bendability, and has high formability. Thus, an alloy plate excellent in BH property and corrosion resistance was obtained.

[0051]

[Table 11]

[0052]

[Table 12]

On the other hand, among the comparative examples, In the case of No. 62, since the heat treatment temperature was lower than the temperature specified in the present invention, the GP zone was generated without dissolving the cluster, the proof stress was increased, and the formability and the bendability were reduced. On the other hand, No. In the case of 63, since the heat treatment temperature is higher than the temperature specified in the present invention,
The yield strength increased, and the formability and bendability decreased. Also,
No. In the case of 64, the heat treatment time is too long.
Zones are generated, the proof stress increases, and the bendability decreases.

(Example 7)
Table 3N shows the hot-rolled alloy sheets within the range specified in the present invention for A4.
o. Intermediate annealing under the conditions shown in No. 27 was performed to produce a cold-rolled sheet having a thickness of 1 mm. Further, in Table 3 No. After performing the solution treatment shown in FIG. 42, and was cooled to around room temperature. The restoration process was performed under the conditions shown in FIG. Thereafter, it was wound up under the conditions shown in Table 13 and cooled to around room temperature. The precipitation state was observed in the same manner as in Example 1, and the mechanical properties, press formability and corrosion resistance were evaluated. As shown in the table, in the present invention, by performing the solution treatment under the conditions shown in the range of the present invention, the ratio of the precipitate occupying the grain boundary is small, and as a result, the precipitate has excellent elongation and bendability, and has high formability. Thus, an alloy plate excellent in BH property and corrosion resistance was obtained.

[0055]

[Table 13]

[0056]

[Table 14]

On the other hand, among the comparative examples, no. In the case of 69, since the winding temperature is lower than the temperature specified in the present invention, clusters are formed during cooling, and the BH property is lower than in the present invention. On the other hand, No. In the case of 70, since the winding temperature was higher than the temperature specified in the present invention, a GP zone was generated during cooling, the proof stress increased, and the bendability decreased. In addition, No. In the case of 71, the cooling rate after winding was too high, clusters were formed, and the BH property was lower than that of the present invention. On the other hand, N
o. In the case of 72, the cooling rate after winding is too slow,
The proof stress increases and the bendability decreases.

[0058]

As described above, according to the present invention, it is possible to provide an aluminum alloy sheet for forming and processing having high BH property and excellent in formability and corrosion resistance.

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Claims (7)

[Claims] 1. Mg: 0.1 to 0.65%, Si: 0.4 to 2%, Cu: 0.8 to 1.4%, Mg + Cu: 0.9 to 1.5% by weight% Zn: 0.03 to 1.5%, Mn: 0.03 to 0.2%, Cr: 0.03 to 0.2%, Zr: 0.03 to 0.15%, V: 0.03 to 0.15%, Fe: 0.03 to 0.3%, Ti: 0.005 to 0.1%, one or more of which are further contained, with the balance being Al and inevitable Alloy containing chemical impurities, and the maximum diameter of a precipitate containing Cu on a crystal grain boundary is 0.5 μm
And less than 5% of the crystal grain interface, and the number of crystal precipitates having a maximum diameter of 0.2 μm or more in the grains is less than 20 per 100 μm ^2. Al-Mg with excellent corrosion resistance and moldability
-Si-Cu alloy plate. 2. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, wherein the solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and the cooling after the solution treatment is performed at a cooling rate of 15 ° C. to 200 ° C. ° C /
A method for producing an Al-Mg-Si-Cu-based alloy sheet having excellent corrosion resistance and formability, characterized in that the time is longer than sec. 3. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, comprising:
A method for producing an Al-Mg-Si-Cu-based alloy sheet, wherein the holding is performed at a temperature lower than 450 ° C for 0.5 to 4 hours. 4. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, wherein the solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and the cooling after the solution treatment is performed at a cooling rate of 15 ° C. to 200 ° C. ° C /
sec, and after winding at 40-100 ° C, 0.1-
A method for producing an Al-Mg-Si-Cu alloy sheet having excellent corrosion resistance and formability, characterized by cooling at a cooling rate of 10 ° C / h. 5. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, wherein the solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and the cooling after the solution treatment is performed at a cooling rate of 15 ° C. to 200 ° C. ° C /
sec, and after winding at 40-100 ° C, 40-1
A method for producing an Al-Mg-Si-Cu-based alloy sheet having excellent corrosion resistance and formability, which is maintained at 00C for 0.5 to 50 hours. 6. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, wherein the solution treatment after cold rolling is performed at 520 ° C. or more and 5 minutes or less, and the cooling after the solution treatment is performed at a cooling rate of 15 ° C. to 200 ° C. ° C /
sec, and after winding at 40-100 ° C, 0.1-
Cool at a cooling rate of 10 ° C./h,
A method for producing an Al-Mg-Si-Cu alloy sheet excellent in corrosion resistance and formability, characterized in that the sheet is heated to 0C and held for more than 0 to 30 minutes. 7. The Al-Mg-Si-C according to claim 1,
A method for producing a u-based alloy sheet, wherein the solution treatment after cold rolling is performed at a temperature of 520 ° C. or more and 5 minutes or less, and the cooling after the solution treatment is performed at a cooling rate of 15 ° C. to 200 ° C. ° C /
sec, and after winding at 40-100 ° C, 0.1-
Cool at a cooling rate of 10 ° C./h,
After heating to 0 ° C and keeping for more than 0 to 30 minutes, 40 to 100 ° C
A method for producing an Al-Mg-Si-Cu alloy sheet excellent in corrosion resistance and formability, wherein the sheet is cooled and wound up, and cooled at a cooling rate of 0.1 to 10 ° C / h.