JPH05125504A - Manufacture of baking hardenability aluminum alloy plate for forming - Google Patents

Abstract

PURPOSE:To provide an alloy plate with excellent formability and high baking hardenability, in the method for manufacturing a baking hardenability aluminum alloy plate for forming suitable for members requiring strength as well as applied with baking finish such as automobile outer plates and plate materials for packaging. CONSTITUTION:An aluminum alloy ingot contg., by weight, 0.2 to 3.0% Si and 0.2 to 3.0% Mg, or furthermore contg. 0.01 to 1.5% Cu and/or <=0.25% Fe or moreover contg. total 0.01 to 1.0% of one or >=two kinds among 0.01 to 0.3% Mn, 0.01 to 0.5% Cr, 0.01 to 0.5% Zr, 0.01 to 0.5% Ti and 0.01 to 0.3% Ni and the balance Al with inevitable impurities is subjected to homogenizing treatment at >=480 deg.C and is thereafter subjected to hot rolling and/or cold rolling. This material is subjected to soln. heat treatment at >=400 deg.C and is cooled at >=3 deg.C/sec cooling rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent bake hardenability and is suitable for members such as automobile outer plates and packaging plates which require strength and are subjected to bake coating. The present invention relates to a method for producing a bake-hardenable aluminum alloy sheet for forming.

[0002]

2. Description of the Related Art Conventionally, cold-rolled steel sheets have been mainly used for outer panels of automobiles, but recently, the use of aluminum alloy sheets has been studied due to the demand for weight reduction of automobile bodies. Has been converted. As a material for automobile skins,
It is required to have excellent press formability, high strength, and excellent corrosion resistance. 5052 alloy (Al-2.5wt% M
g-0.25 wt% Cr), 5182 alloy (Al-0.35 wt% Mn-
0.45wt% Mg) and other Al-Mg alloys (5000 series alloys)
6009 alloy (Al-0.8wt% Si-0.6wt% Mg-0.
27wt% Cu-0.5wt% Mn), 6061 alloy (Al-0.6wt
% Si-0.1wt% Mg-0.27wt% Cu-0.2wt% Cr)
Al-Mg-Si alloys (6000 series alloys) have been used.

[0003]

The above-mentioned 6000 series alloys have good press formability and can obtain high strength after baking coating, and are therefore applied to automobile outer panel materials. However, the conventional baking temperature was 180 ° C for about 1 hour, but as the baking temperature tends to be low and the baking time tends to be shortened, high strength after baking is required. The heat treatment type aluminum alloy plate used for such purpose is subjected to solution treatment by continuous annealing equipment.
However, this method has a drawback that the solution treatment is not sufficiently performed because the solution temperature is maintained for a short time.

[0004]

As a result of various studies in view of the above, the present invention has developed a method for producing a bake hardenable aluminum alloy sheet for bake hardenability, which facilitates solution treatment in continuous annealing equipment and has a high bake hardenability. It was done.

That is, one of the present inventions is that Si 0.2-3.0 wt%
(Hereinafter, wt% is abbreviated as%), Mg 0.2 to 3.0%, and an aluminum alloy ingot containing the balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C. or higher, and then hot rolled and And / or cold-rolled material is subjected to solution treatment at a temperature of 400 ° C. or higher and cooled at a cooling rate of 3 ° C./sec or higher.

Another aspect of the present invention is Si 0.2-0.3%,
Mg 0.2-3.0%, Cu 0.01-1.5%, balance Al
And aluminum alloy ingot consisting of inevitable impurities,
After homogenizing at 80 ° C or higher, hot-rolled and / or cold-rolled material is subjected to solution heat treatment at 400 ° C or higher and cooled at 3 ° C / sec or higher. It is characterized by cooling.

Another aspect of the present invention is Si 0.2 to 0.3.
%, Mg 0.2 to 3.0%, Fe 0.25% or less, and M
n0.01-0.3%, Cr0.01-0.5%, Zr0.01-0.5
%, Ti 0.01 to 0.5%, Ni 0.01 to 0.3%, one or more of 0.01 to 1.0% in total, and the balance of aluminum and inevitable impurities in an aluminum alloy ingot, at 480 ° C or higher. After homogenizing at temperature, hot-rolled and / or cold-rolled material is subjected to solution heat treatment at a temperature of 400 ℃ or more and cooled at a cooling rate of 3 ℃ / sec or more. It is a feature.

Still another aspect of the present invention is that Si 0.2 to 0.3
%, Mg 0.2-3.0%, Cu 0.01% -1.5%, Fe0.25
% Or less, Mn 0.01 to 0.5%, Cr 0.01 to 0.5
%, Zr0.01-0.5%, Ti0.01-0.5%, Ni0.01-
After performing homogenization treatment at a temperature of 480 ° C. or higher on an aluminum alloy ingot containing 0.3 to 1% or more of 0.01% to 1.0% in total and the balance Al and unavoidable impurities.
It is characterized in that the material that has been hot-rolled and / or cold-rolled is subjected to solution treatment at a temperature of 400 ° C. or higher and cooled at a cooling rate of 3 ° C./sec or higher.

[0009]

In the present invention, the alloy composition is limited as described above for the following reason.

Si is Mg ₂ S together with Mg during baking coating.
i is deposited to improve the strength. However, the addition amount is limited to 0.2 to 3.0% because if it is less than 0.2%, the hardening is small, and if it exceeds 3.0%, the formability after solution treatment is deteriorated.

Mg forms a solid solution in the matrix after the solution treatment and contributes to the improvement of formability, and Mg ₂ Si precipitates together with Si during baking coating to improve the strength. However, the addition amount is limited to 0.2 to 3.0% because if it is less than 0.2%, its effect is small, and if it exceeds 3.0%, the formability after solution treatment is deteriorated.

[0012] As described above, Si and Mg are precipitated as Mg ₂ Si during baking coating to improve the strength. However, when the abundance ratios of these two elements are different, the bake hardenability is also different, and the weight ratio of Si and Mg is Si> 0.6Mg (%), M
If the amount of Si is excessive with respect to the amount of g ₂ Si, more excellent bake hardenability can be obtained.

Incidentally, in order to control the aging behavior during baking coating, addition of Ag, Cd, etc. does not impair the effect of the present invention.

Cu is applied to the GP zone, θ ',
Precipitation of S phase etc. improves strength. However, the addition amount is limited to 0.01 to 1.5% because if it is less than 0.01%, the strength is not improved so much, and if it exceeds 1.5%, the corrosion resistance is lowered and the quenching sensitivity becomes too high.

Fe is usually contained as an impurity of Al. Therefore, Fe is easy to form a compound with Si,
If the content exceeds 0.25%, the improvement in strength during baking coating is hindered.

Mn, Cr, Zr, Ti and Ni are added to refine the crystal grains or improve the strength of the matrix. However, the amount of each additive is limited as described above because if the amount is less than the lower limit, the effect is small, and if the amount exceeds the upper limit, the formability after solution treatment decreases. Further, the total amount of these elements is limited to 0.01 to 1.0% because if it is less than the lower limit, the effect is small, and if it exceeds the upper limit, the formability after solution treatment is lowered.

If B or the like, which is usually added as a refiner of the cast structure, is 0.1% or less, the effect of the present invention is not particularly impaired.

Next, the manufacturing process will be described. The present invention, after homogenizing the aluminum alloy ingot having the above composition at a temperature of 480 ° C. or higher, hot rolling and cold rolling according to a conventional method,
Or cold-roll it into a plate with the desired dimensions,
Solution treatment is performed at a temperature of ℃ or more, and the solution is cooled at a cooling rate of 3 ℃ / sec or more.

In the homogenizing treatment, the non-equilibrium primary crystal compound at the time of casting is dissolved in the matrix to reduce the amount of coarse Si and Mg compounds, and the solid solution can be promptly dissolved during the solution treatment. The temperature is set to 480 ° C. or higher because at a temperature lower than 480 ° C., precipitation of Si and Mg promotes coarsening of the compound, which makes rapid solution treatment difficult and makes it difficult to improve strength after baking. This is because it will be sufficient. The holding time is not particularly specified, but it is preferably 1 hour or more.

The solution treatment is to improve the strength by temporarily dissolving the additive elements such as Si and Mg in the matrix and precipitating fine compounds such as Mg ₂ Si during the heating for baking and coating. Then, the solution treatment temperature was 400 ℃
The reason for the above is that the additive element cannot be sufficiently solid-solved at a temperature of less than 400 ° C., and the improvement in strength during baking heating is small. The holding time is not specified, but 400
It is preferable that the time at which the temperature is not lower than 0 ° C. is not shorter than 5 seconds. The cooling rate after solution treatment was set to 3 ° C./sec or more,
This is because when the cooling rate is less than 3 ° C./sec, a coarse compound precipitates, resulting in a decrease in moldability and a decrease in strength after heating by baking coating.

[0021]

EXAMPLES The present invention will be described below with reference to examples. Table 1
The aluminum alloy having the composition shown in FIG.
An ingot was obtained by C casting. The ingot was homogenized under the conditions shown in Table 2. After that, hot-rolled and cold-rolled to form a plate with a thickness of 1 mm, and kept at a temperature of 520 ° C for 15 seconds,
A solution treatment for cooling at 30 ° C./sec was performed to produce a bake-curable aluminum plate for forming.

A tensile test, an Erichsen bulge test, and a limit deep drawing (LDR) test were conducted on the plate material thus manufactured. Also simulated the baking coating process 1
Tensile tests were also conducted after heating for 60 min at 50 ° C, 180 ° C, and 200 ° C. The results are shown in Table 3.

In the tensile test, tensile strength, proof stress and elongation were measured using JIS No. 5 tensile test pieces. Erichsen overhang test
The overhang height was measured by the JIS Z2247A method. In the limit deep drawing (LDR) test, a blank having lubrication oil applied was deep-drawn with a punch having a diameter of 33 mm, and the maximum blank diameter without breaking was divided by the punch diameter to obtain a value.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

As is clear from Table 3, the plate materials produced according to the examples of the present invention are excellent in formability after solution treatment and strength after baking coating treatment. On the other hand, the plate material according to the comparative example deviating from the production method of the present invention is inferior in at least one of the formability after the solution treatment and the strength after the baking coating treatment.

[0028]

As described above, according to the present invention, it is possible to obtain an aluminum alloy sheet for forming which has excellent formability and high bake hardenability, and has a remarkable industrial effect.

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[Procedure amendment]

[Submission date] February 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Another aspect of the present invention is Si0.2 to 3.0.
%, Mg 0.2-3.0%, Cu 0.01-1.5%, and aluminum alloy ingot consisting of balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C. or higher, The material that has been hot-rolled and / or cold-rolled has a 40
The solution treatment is performed at a temperature of 0 ° C. or higher, and the solution is cooled at a cooling rate of 3 ° C./sec or higher.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

According to another aspect of the present invention, Si0.2 to
3.0, Mg 0.2-3.0%, Fe 0.25% or less, Mn 0.01-0.3%, Cr 0.01-
0.5%, Zr 0.01 to 0.5%, Ti 0.01 to
480 ° C. to an aluminum alloy ingot containing 0.5% and 0.01 to 0.3% of Ni and 0.01 to 1.0% in total, and the balance of Al and inevitable impurities.
After the homogenization treatment at the above temperature, the material that has been hot-rolled and / or cold-rolled is subjected to solution treatment at a temperature of 400 ° C. or higher and cooled at a cooling rate of 3 ° C./sec or higher. It is characterized by that.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Another aspect of the present invention is that Si0.2 to
3.0 wt%, Mg 0.2-3.0%, Cu 0.01%
.About.1.5%, Fe 0.25% or less, and Mn0.
01-0.3%, Cr 0.01-0.5%, Zr0.0
1-0.5%, Ti0.01-0.5%, Ni0.01
~ 0.01% of one or two or more out of 0.3%
Aluminum alloy ingot containing 1.0% and balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C. or higher, and then hot-rolled and / or cold-rolled. Solution treatment is applied at a temperature of 400 ° C or higher, 3 ° C /
It is characterized by cooling at a cooling rate of sec or more.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kunihiko Kishino 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Aluminum Co., Ltd. (72) Inventor Gen Watanabe 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Aluminum Co., Ltd.

Claims (4)

[Claims] 1. Si 0.2-3.0 wt%, Mg 0.2-3.0 wt
%, And the aluminum alloy ingot containing the balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C. or higher, and then hot-rolled and / or cold-rolled.
A method for producing a bake-hardenable aluminum alloy sheet for forming, which comprises subjecting the solution treatment to a temperature of 00 ° C or more and cooling at a cooling rate of 3 ° C / sec or more. 2. Si 0.2-3.0 wt%, Mg 0.2-3.0 wt
%, Cu 0.01 to 1.5 wt%, and aluminum alloy ingot consisting of balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C or higher, and then hot-rolled and / or cold-rolled. A method for producing a bake-hardenable aluminum alloy sheet for forming, which comprises subjecting the applied material to a solution treatment at a temperature of 400 ° C or higher and cooling it at a cooling rate of 3 ° C / sec or higher. 3. Si 0.2-3.0 wt%, Mg 0.2-3.0 wt
%, Fe 0.25 wt% or less, and Mn 0.01 to 0.3 wt
%, Cr 0.01 to 0.5 wt%, Zr 0.01 to 0.5 wt%, Ti0.
01-0.5wt%, Ni 0.01-0.3wt%, 1 type or 2 types or more of 0.01-1.0wt% in total, the balance of Al and unavoidable impurities in the aluminum alloy ingot, the temperature of 480 ℃ or more Characterized by subjecting the material that has been subjected to homogenization treatment to hot rolling and / or cold rolling to a solution treatment at a temperature of 400 ° C or higher and cooling at a cooling rate of 3 ° C / sec or higher. And a method for producing a bake-hardenable aluminum alloy sheet for forming. 4. Si 0.2-3.0 wt%, Mg 0.2-3.0 wt
%, Cu 0.01 to 1.5 wt%, Fe 0.25 wt% or less, Mn 0.01 to 0.5 wt%, Cr 0.01 to 0.5 wt%, Zr 0.01
~ 0.5wt%, Ti0.01 ~ 0.5wt%, Ni0.01 ~ 0.3wt%
1 type or 2 types or more of them, including 0.01 to 1.0 wt% in total,
Aluminum alloy ingot consisting of balance Al and unavoidable impurities is homogenized at a temperature of 480 ° C or higher, and then hot-rolled and / or cold-rolled material is melted at a temperature of 400 ° C or higher. A method for producing a bake hardenable aluminum alloy sheet for forming, which comprises subjecting to a heat treatment and cooling at a cooling rate of 3 ° C./sec or more.