JPH0971831A - Gray-colored aluminum alloy plate with little yellow and reddish color after anodizing treatment and method for producing the same - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To obtain a gray coloring alloy which suppresses yellowness and redness, which gives a feeling of cleanliness, luxury and stability. SOLUTION: 1. Mg 0.5 to 3.5%, Mn
0.29 to 0.49%, Fe, Ti, and B are contained, and Si, Cu, and Cr are regulated to a certain value or less, and the balance is Al and inevitable impurities, and 0.03
The distribution density of the intermetallic compound having a size within the range of up to 2.5 μm is within the range of 10 ³ to 10 ⁸ pieces / mm ² , and 60 of them are distributed.
% Or more is an Mn-based intermetallic compound, an aluminum alloy plate. A pre-heat treatment, a heat treatment, a hot rolling, an intermediate annealing in the middle of cold rolling, and a final cold rolling are performed on the ingot of the aluminum alloy having the composition of claim 1 under a certain condition, and thereby a desired structure is obtained. To produce an aluminum alloy plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy material for use after being subjected to anodizing treatment, in particular, building materials such as building curtain oars, building exterior materials and interior materials, or equipment, containers, and various electric equipment. The present invention relates to an aluminum alloy used for a housing, an outer plate and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art Aluminum alloys generally used for building materials such as curtain oars, building exterior materials and interior materials, or for vessels, containers, casings of electrical equipment, outer plates, etc. are anodized from the viewpoint of aesthetics and corrosion resistance. Often used. Many of the aluminum alloys for anodic oxidation treatment for these uses have a light gray to silver color tone after anodization treatment.
Typical examples are IS 1050 alloy, 1100 alloy, 5005 alloy, and the like. Al-1 to 4% Si alloy is generally used as a gray-based color tone after anodizing.

[0003]

Among the various color tones, gray tones (gray tones) give a calm texture, and are therefore preferred for use as building materials such as curtain oars, exterior materials and interior materials. There are many. Of the gray tones, yellow or reddish gray often gives a light or cheesy impression, while
On the contrary, gray that suppresses yellowness and redness gives a feeling of cleanliness, luxury, and stability, so gray that suppresses yellowness and redness is required for gray materials used for building materials. Is increasing.

By the way, the conventional Al-- which is known to obtain a grayish color tone as a color tone after anodizing treatment
Si-based alloys have a strong yellowish color, but on the other hand, redness tends to be stronger if the yellowing is attempted. Therefore, in the conventional Al-Si alloy, the color tone after anodizing treatment is
It has been difficult to reliably and stably obtain a gray color tone that suppresses yellowness and redness.

In addition, in the conventional Al--Si alloy, S
Since a large amount of i is contained, dismutability during anodic oxidation treatment is poor, and therefore, there is a problem that it takes time to remove smut, and therefor it is possible to obtain a gray color tone with an alloy of a system other than Al-Si system. Is desired.

The present invention has been made in view of the above circumstances, and as an aluminum alloy plate used by anodizing a building material or the like, particularly, it has a gray color tone which suppresses yellowing and redness after the anodizing treatment. It is an object of the present invention to provide an aluminum alloy plate and a manufacturing method thereof.

[0007]

In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive experiments and studies, and as a result, Mg and Mn are appropriately blended as alloy composition and at the same time the manufacturing process is performed. By properly controlling and adjusting the distribution density of the intermetallic compound of a specific size appropriately, it was found that a gray color with suppressed yellowing and redness can be obtained as a color tone after anodizing treatment. Invented.

Specifically, the aluminum alloy sheet according to the first aspect of the invention has Mg 0.5 to 3.5% (weight%, the same hereinafter), Mn 0.29 to 0.49%, Fe 0.04 to 0.
20%, Ti 0.003 to 0.20%, B 0.0001
.About.0.0100%, restricting Si to 0.14% or less, Cu to 0.14% or less, and Cr to 0.14% or less, with the balance being Al and inevitable impurities, and 0. The distribution density of the intermetallic compound having a size within the range of 0.03 to 2.5 μm is within the range of 10 ³ to 10 ⁸ pieces / mm ² , and 60% or more of them are Mn-based intermetallic compounds. The aluminum alloy plate has a gray color with little yellowness and redness after anodizing.

The method of manufacturing an aluminum alloy plate according to the second aspect of the present invention is such that Mg 0.5 to 3.5% and Mn 0.29 to
0.49%, Fe 0.04 to 0.20%, Ti 0.00
3 to 0.20%, B 0.001 to 0.0100%, and Si is regulated to 0.14% or less, Cu is regulated to 0.14% or less, and Cr is regulated to 0.14% or less. A
1 and the inevitable impurities of an aluminum alloy ingot were preheated at 400 to 600 ° C. for 2 to 24 hours, and then at 350 to 530 ° C. for 0.
After heat treatment for 5 to 24 hours, 350 to 530
The hot rolling is started at a temperature in the range of ℃, further intermediate annealing of 250 to 500 ° C. × 0.5 to 24 hours is performed in the middle of the cold rolling, and then the final cold rolling of the rolling ratio of 85% or less is performed. As a result, the distribution density of the intermetallic compound having a size in the range of 0.03 to 2.5 μm is 10 ³ to 10 ⁸ pieces / mm ^2.
Within a range of 60% or more of which is a Mn-based intermetallic compound, which is a method for producing a gray-colored aluminum alloy plate with little yellowness and redness after anodizing. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the aluminum alloy sheet of the present invention, in order to obtain a gray color tone with suppressed yellowishness and redness as a color tone after anodizing treatment, an alloy component composition,
The state of precipitation of intermetallic compounds is important. Therefore, first, the reason for limiting the alloy composition will be described.

Mg: Mg is an alloying element that contributes to the improvement of strength and is necessary for satisfying the strength required for building materials, etc., and also promotes the precipitation of Mn-based intermetallic compounds, It is involved in determining the color tone after the anodizing treatment. That is, the distribution density of the Mn-based intermetallic compound is adjusted by changing the Mg content, and light gray to dark gray colors can be obtained after the anodizing treatment. If the amount of Mg is less than 0.5%, these effects are not sufficiently obtained, while if the amount of Mg exceeds 3.5%, it is effective in darkening the color tone after anodizing treatment, but bending Sex significantly decreases. Therefore, the amount of Mg is set within the range of 0.5 to 3.5%.

Mn: Mn is an important element for determining the color tone after anodizing treatment in the present invention. That is, Mn is an Mn-based intermetallic compound {Al ₆ Mn, Al ₆ (Mn
Fe) and the like}, and these Mn-based intermetallic compounds remain in the anodized film even after the anodizing treatment and contribute to obtaining a gray color tone. The present inventors have found that the size and distribution density of the Mn-based intermetallic compound have a great influence on the color tone after anodizing treatment, and by controlling these appropriately, a color tone from light gray to dark gray can be obtained. It was That is, the size of the Mn-based intermetallic compound is 0.
Within the range of 03 to 2.5 μm, the distribution density of intermetallic compounds is within the range of 10 ³ to 10 ⁸ pieces / mm ² , of which 60%
The above is required to be the Mn-based intermetallic compound. M
When the n content is less than 0.29%, it is difficult to achieve the above-described distribution state, and the gray color tone becomes too light after the anodizing treatment. On the other hand, if the amount of Mn exceeds 0.49%, the amount of Mn-based intermetallic compound is too large, which causes rough skin and deterioration of bendability. Therefore, the amount of Mn is 0.29 to 0.4
It was set within the range of 9%.

Fe: Fe is an element that contributes to the refinement of crystal grains during intermediate annealing, and also Al ₆ (MnFe), A
It contributes to the shade of gray in the form of ₁₆ Fe. If it is less than 0.04%, the above effect is insufficient, and if it exceeds 0.2%, Al ₃
The amount of Fe crystallized substance increases, and color unevenness and streak defects are likely to occur on the surface after anodizing treatment.
The range was up to 0.2%.

Ti, B: Ti has the effect of refining the crystal grains of the ingot and preventing streaks and texture of the rolled plate, but if Ti is less than 0.003%, the effect cannot be obtained, while Ti is If it exceeds 0.20%, a TiAl ₃ -based coarse intermetallic compound is generated, so that Ti is 0.003 to
It was set within the range of 0.20%. B is an element that coexists with Ti and promotes grain refinement, and is sometimes added in combination with Ti. However, when the B content is less than 0.0001%, the effect cannot be obtained, while when it exceeds 0.0100%, the effect is saturated, and coarse TiB ₂ particles are generated to generate linear defects. B added in combination
Was in the range of 0.0001 to 0.0100%.

Si: If Si is 0.14% or less, there is no substantial influence on the color tone after anodizing. However, if Si exceeds 0.14%, a large amount of Si-based intermetallic compounds are generated, and the yellow or redness becomes strong in the color tone after anodizing treatment, and the yellowness and redness that are the objectives of the present invention are suppressed. It will not be possible to achieve a gray tone. Therefore, it is necessary to regulate the Si amount to 0.14% or less.

Cr, Cu: If Cr or Cu is 0.14% or less, it does not have a substantial effect on the color tone after anodizing treatment, but if it exceeds 0.14%, the gray color tone becomes more yellowish. , 0.14% or less.

In addition, in Al--Mg type alloys,
Although a small amount of Be has been conventionally added to prevent the oxidation of the molten metal, it is not particularly problematic to add Be of about 500 ppm or less in the case of the aluminum alloy of the present invention.

Further, a general aluminum alloy may contain Zr, V, Zn, etc., but these are 0 and Zr and V within a range that does not impair the effects of the present invention, especially the color tone after anodizing. It is allowed to contain 0.2% or less and Zn of 2% or less.

Further, in the aluminum alloy sheet of the present invention, not only the alloy composition as described above but 0.03
It is necessary that the distribution density of the intermetallic compound having a size within the range of up to 2.5 μm is within the range of 10 ³ to 10 ⁸ pieces / mm ² , and 60% or more of them is the Mn-based intermetallic compound. . If the distribution density of the intermetallic compound is less than 10 ³ pieces / mm ² , the color tone after the anodizing treatment becomes too light, while 10 ⁸
If the number of particles / mm ² is exceeded, not only the bending workability is deteriorated, but also the color tone tends to be yellow or red. Also,
The density of the Mn-based intermetallic compound is the distribution density of the intermetallic compound 1
If it does not occupy 60% or more of 0 ³ to 10 ⁸ pieces / mm ² , it is difficult to obtain a gray color tone. The intermetallic compound having a size smaller than 0.03 μm does not significantly affect the color tone after the anodizing treatment. On the other hand, if there are many coarse intermetallic compounds exceeding 2.5 μm, the number tends to decrease, and in this case, it becomes difficult to satisfy the distribution density condition of 10 ³ pieces / mm ² or more. Therefore, in the present invention, 0.03 to 2.5 μm
It was decided to define the distribution density of the intermetallic compound of the size of.

As described above, in order to achieve the size and distribution density of the intermetallic compound, the alloy component composition, especially Mn, M
While properly adjusting the g content,
In particular, it is necessary to appropriately control the heating before hot rolling.

The method for producing the aluminum alloy plate of the present invention will be described below.

First, an alloy having the above-described composition is cast by a conventional method. As a casting method, a DC casting method (semi-continuous casting method) is generally used, but a thin plate continuous casting method (continuous casting rolling method) can also be applied.

The obtained cast material is first subjected to preheating treatment. This pre-heating treatment eliminates the segregation of elements to bring about a homogenizing effect as in the case of a normal ingot homogenizing treatment (soaking treatment), and at the same time, the effect of a precipitation treatment for precipitating a Mn-based intermetallic compound is achieved. Is also aimed at. This pre-heating treatment is 2 to 2 at a temperature in the range of 400 to 600 ° C.
It needs to be heated for 4 hours. If the temperature is lower than 400 ° C, the effect of precipitation is obtained, but the homogenizing effect becomes insufficient, while if it exceeds 600 ° C, a eutectic melting reaction may occur. When the time is less than 2 hours, the homogenizing effect and the precipitation effect are not sufficient, while the heating for a long time exceeding 24 hours only impairs the economical efficiency.

After the preheating treatment as described above, as the heating treatment before hot rolling, heating is performed at a temperature in the range of 350 to 530 ° C. for 0.5 to 24 hours. This heat treatment
This is an important step not only for obtaining the temperature for starting hot rolling but also for obtaining an appropriate precipitation state of an appropriate Mn-based intermetallic compound, and sufficient precipitation can be achieved by heating at a relatively low temperature for a long time. Plan. That is, M that is in solid solution
When n is sufficiently precipitated at this stage, the distribution density of the intermetallic compound having a size of 0.03 to 2.5 μm in the state of the final plate is 10 ³ to 10 ⁸ pieces / mm ² , and 60% or more thereof Is controlled to be a Mn-based intermetallic compound. If the temperature of this heat treatment is less than 350 ° C., hot rolling becomes difficult, while if the temperature exceeds 530 ° C., sufficient precipitation cannot be achieved. Further, if the time is less than 0.5 hours, sufficient precipitation cannot be achieved, while if it exceeds 24 hours, the effect of precipitation is saturated and the economical efficiency is only lowered.

As described above, heat treatment is performed at a temperature in the range of 350 to 530 ° C., and then hot rolling is started at that temperature. This hot rolling may be performed according to a conventional method.

The intermediate annealing is not particularly required from the viewpoint of the color tone after the anodizing treatment, but bendability, flatness, etc. are important in the application of building materials such as curtain oars, and in order to secure these, the intermediate annealing is performed. Do. This intermediate annealing is 250
The temperature is kept within a range of up to 500 ° C for 0.5 to 24 hours, and when the temperature is lower than 250 ° C, recrystallization is not sufficiently performed, and when the temperature is higher than 500 ° C, Mn is re-dissolved to give a predetermined intermetallic content. The density of the compound cannot be obtained, and the color tone after anodizing becomes too light. Even if the intermediate annealing time is less than 0.5 hours, recrystallization is not sufficiently performed, while holding for more than 24 hours is economically useless.

The final cold rolling after the intermediate annealing has a rolling ratio of 85.
% Or less. When the final cold rolling rate exceeds 85%, bending workability as a building material is deteriorated, and material cracking due to bending is likely to occur.

By applying the above process, finally, the distribution density of the intermetallic compound having a size of 0.03 to 2.5 μm is 10 ³ to 10 ⁸ / mm ² , and 60% or more of the distribution density is obtained. A rolled plate that is a Mn-based intermetallic compound can be obtained.

The specific method for anodizing the rolled plate obtained as described above is not particularly limited, but in the case of the rolled plate according to the present invention, a sulfuric acid electrolytic bath with good economy is used. By the anodizing treatment used, it is possible to surely and stably obtain a gray color tone with suppressed yellowing and redness.

The color tone after the anodizing treatment can be evaluated by the values of the lightness index L and the chromaticness indices a and b according to Hunter's color difference formula (see JIS Z8730). That is, the higher the value of the lightness index L is, the whiter it is, while the chromaticness index is the degree of coloring, the higher the value of a is, the more reddish the color is; The lower the value, the stronger the blueness. And the gray color tone which suppresses the yellowishness and the reddishness, which is the object of the present invention, is L value, a value, b
It can be defined as a color tone whose value satisfies 50 <L <75 −2.5 <a <2.5 −2.5 <b <2.5.

[0031]

EXAMPLES Alloys Nos. 1 to 4 shown in Table 1 D
The slab was cast by the C casting method, preheated under the conditions shown in Table 2, further subjected to surface cutting, and then subjected to heat treatment before hot rolling under the conditions shown in Table 1 and subjected to hot rolling to 6.0 m.
A hot rolled sheet having a thickness of m was obtained. Each hot-rolled sheet was subjected to primary cold rolling to a thickness of 2.8 mm, then subjected to intermediate annealing as shown in Table 2, and then finally cold rolled to a thickness of 2.5 mm.

[0032]

[Table 1]

[0033]

[Table 2]

Then, 10% NaO was applied to each rolled plate.
It was etched with an aqueous solution of H, washed with water, and then subjected to dismutation treatment with nitric acid. Then, using a sulfuric acid electrolytic bath having a H ₂ SO ₄ concentration of 15 vol%, a current density of 1.5 A / dm ² and a bath temperature of 20
Anodic oxidation treatment is performed at a temperature of ℃
Of the anodic oxide film was generated.

The color tone of each rolled plate after anodizing was examined using a Hunter color meter (SM-3-MCH), and evaluated by the L value, a value, and b value by the Hunter color difference formula. Further, the bendability was evaluated by performing hem bending at 90 ° and a radius of 0.1R. Further, for each rolled plate, 0.
The distribution density of the intermetallic compound having a size of 03 to 2.5 μm was examined. Table 3 shows the results. Note that the distribution density of the intermetallic compound was 10, 10, using a transmission electron microscope.
The average distribution density was obtained by observing 15 fields of view at a magnification of 000 times. Further, the size of the intermetallic compound was examined by the size of the diameter of the circle when it was replaced with a circle having an area equal to the area of the precipitate. The components of the intermetallic compound are 10,000 to 100,000 using a transmission electron microscope.
It was examined at double magnification.

[0036]

[Table 3]

As can be understood from the results of Table 3, the composition of the alloy is controlled to satisfy the range specified by the present invention, and the manufacturing process is controlled so as to satisfy the conditions specified by the present invention. The rolled plate (manufacturing number 1) in which the distribution density of the intermetallic compound of 0.5 μm was in the range of 10 ³ to 10 ⁸ pieces / mm ² had a gray color tone with suppressed yellowing and redness after the anodizing treatment. was gotten.

On the other hand, in the case of production number 2, the alloy component composition is within the range specified by the present invention, but since the intermediate annealing temperature is too high, Mn is re-dissolved and the distribution of Mn-based intermetallic compound is distributed. Density is 60% of distribution density of intermetallic compound
Therefore, the color tone after anodizing became silver rather than gray. Also in the case of production number 3, since the Cr content was too high, the color tone after anodizing was strongly yellowed, and the Mg content was too high, resulting in poor bendability. In Production No. 4, since Mn was too much, the occurrence of rough skin and the deterioration of bendability were observed. And serial number 5
In the case of Si, Cu, and Cr, the amount of Si, Cu, and Cr added was too large, so that the color tone after anodizing treatment had a strong yellowish tint.

[0039]

The rolled aluminum alloy plate of the present invention is
By properly defining the component composition of the alloy and adjusting the size and distribution range of the intermetallic compound precipitates, the tone after the anodizing treatment is assured of a gray color with less yellow and redness. And it can be obtained stably. Further, in particular, according to the manufacturing method of the invention of claim 2, it is possible to reliably and stably manufacture a rolled aluminum alloy plate having a dispersion state of an intermetallic compound suitable for obtaining the color tone as described above on a mass production scale. it can.

Claims (2)

[Claims] 1. Mg 0.5 to 3.5% (weight%, the same hereinafter), Mn 0.29 to 0.49%, Fe 0.04 to 0.
20%, Ti 0.003 to 0.20%, B 0.0001
.About.0.0100%, restricting Si to 0.14% or less, Cu to 0.14% or less, and Cr to 0.14% or less, with the balance being Al and inevitable impurities, and 0. The distribution density of the intermetallic compound having a size within the range of 0.03 to 2.5 μm is within the range of 10 ³ to 10 ⁸ pieces / mm ² , and 60% or more of them are Mn-based intermetallic compounds. A gray-colored aluminum alloy plate that has little yellow and red tones after anodizing. 2. Mg 0.5-3.5%, Mn 0.29-
0.49%, Fe 0.04 to 0.20%, Ti 0.00
3 to 0.20%, B0.0001 to 0.0100%, and Si is regulated to 0.14% or less, Cu is regulated to 0.14% or less, and Cr is regulated to 0.14% or less. A
1 and the inevitable impurities of an aluminum alloy ingot were preheated at 400 to 600 ° C. for 2 to 24 hours, and then at 350 to 530 ° C. for 0.
After heat treatment for 5 to 24 hours, 350 to 530
The hot rolling is started at a temperature in the range of ℃, further intermediate annealing of 250 to 500 ° C. × 0.5 to 24 hours is performed in the middle of the cold rolling, and then the final cold rolling of the rolling ratio of 85% or less is performed. As a result, the distribution density of the intermetallic compound having a size in the range of 0.03 to 2.5 μm is 10 ³ to 10 ⁸ pieces / mm ^2.
Within the range, a rolled plate having 60% or more of which is a Mn-based intermetallic compound is obtained, and a method for producing a gray-colored aluminum alloy plate having little yellowing and redness after anodizing.