JP2544235B2 - High strength aluminum alloy wrought material with gray color after anodizing treatment and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-strength aluminum alloy wrought material for use in which anodizing treatment is applied, particularly a building material such as a building curtain wall, building exterior material, interior material, Or something,
The present invention relates to a high-strength aluminum alloy wrought material used as an extruded shape material or a rolled material for a container, an electric measuring instrument housing, a name plate, and the like, and a method for manufacturing the same.

Conventional technology In general, curtain walls, building exterior materials, building materials such as interior materials, or wrought aluminum alloy materials used for vessels, containers, electrical measuring instrument housings, name plates, etc., that is, extruded shape materials and rolled materials, From the viewpoint of corrosion resistance, it is often used after being anodized. As anodized aluminum alloys for these applications, the color tone after anodization is often light gray to silver, and as rolled materials of such alloys, generally JIS 1050 alloy, 1100 alloy, 50
05 alloys are often used, and extruded profiles such as sashes are often 6063 alloys. In addition, as a gray type, Al-
1 to 4% Si alloy is common. In addition, as an aluminum alloy with a gray color tone after anodizing treatment, Al-Fe
Based alloys and Al-Fe-Mg-Mn alloys have been proposed.
As an anodizing method, an anodizing method using a sulfuric acid electrolytic bath has been generally used conventionally from the viewpoint of economy and corrosion resistance.

Problems to be Solved by the Invention Among various color tones, the gray color tone gives a soothing texture, so that the gray color tone is often required also in applications such as building materials.

However, Al-Si-based aluminum alloy has poor desmutting property, and there is a problem that the surface after anodizing treatment is powdery, and the color tone after anodizing treatment is yellowish or grayish although it is grayish. It is often desired to have an achromatic gray color with a strong reddish color.

On the other hand, in the case of Al-Fe-based alloys and Al-Fe-Mg-Mn-based alloys, the drawbacks of Al-Si-based alloys as described above can be compensated, but as extruded shape members such as sashes, the strength is high. There is a problem that it cannot be applied because it is insufficient, and is unsuitable when high strength is required as a rolled material.

This invention was made against the background of the above circumstances.
As a color tone after anodizing treatment, a gray color not having a yellowish or reddish tone, that is, an achromatic gray color tone can be stably obtained, and an aluminum alloy wrought material having sufficient high strength and its production It is intended to provide a method.

Means for Solving the Problems The inventors of the present invention have conducted various experiments and studies on the means for solving the above-mentioned problems, and as a result, appropriately adjust the alloy components to obtain Mn.
The inventors have found that by controlling the precipitates, the anodic oxide film can be made an achromatic gray color and at the same time high strength can be obtained, and the present invention has been completed.

Specifically, the aluminum alloy wrought material of the invention of claim 1 has Mn 0.5 to 2.0 wt%, Mg 0.5 to 2.0 wt%, and Zn 1.0 to 5.
It contains 5wt% and Ti 0.003〜 as a grain refiner.
0.15 wt% is contained alone or in combination with B 1 to 100 ppm, and the balance is made up of Al and other unavoidable impurities. It is possible to obtain an achromatic gray color and high strength as the color tone after the oxidation treatment.

Further, the invention of claim 2 relates to a method for manufacturing extruded shape material among wrought materials, in which an alloy having the same composition as the above is cast by a DC casting method, and then an ingot is made to have a size of 400 to 6
By heating to a temperature in the range of 00 ℃ for 0.5 to 24 hours, then performing hot extrusion and cooling immediately after the hot extrusion at a cooling rate of 20 ℃ / min or more, there is no color tone after anodizing treatment. An extruded aluminum alloy profile that is colored gray and has high strength is obtained.

Further, the invention of claim 3 relates to a method for producing a rolled material among the wrought materials, in which an alloy having the same composition as the above is cast by a DC casting method, and then an ingot is made to have a thickness of 400 to 600.
Heat at a temperature in the range of ℃ for 0.5 to 24 hours, and then perform hot rolling, or hot and cold rolling, and a temperature in the range of 350 to 600 ℃ after hot rolling or after cold rolling. By heating to 20 ° C./min or more and cooling at a cooling rate of 20 ° C./min or more, a rolled material having an achromatic gray color after anodizing treatment and having high strength is obtained.

Action First, the reasons for limiting the component composition in the wrought aluminum alloy material of the present invention will be explained.

Mn: Mn is an important element for forming an Al-Mn-based intermetallic compound and determining the color tone after anodizing treatment, and the present inventors have found that Mn-containing precipitates (Al ₆ Mn, AlMnSi, AlMnFe, AlM
It was found that the type and size of (nFeCr, etc.) are important for making the color tone of the anodized film achromatic gray. Ie
When Mn coexists with Mg, precipitation of Mn-based precipitates of a predetermined size is achieved, and the anodized film has a grayish color tone. If the amount of Mn is less than 0.5 wt%, sufficient graying cannot be achieved, while if the amount of Mn exceeds 2.0 wt%, graying is possible, but primary crystal intermetallic compounds are formed during DC casting. Therefore, the Mn content is limited to the range of 0.5 to 2.0 wt%.

Mg: Mg is an element necessary to promote the precipitation of Mn and generate Mn-based precipitates of a predetermined size. Especially when the cooling rate during casting is slow compared to thin film continuous casting like DC casting and the amount of forced solid solution of Mn is small, the size of Mn-based precipitates is anodized unless some Mg is contained. After processing, it is not in a state suitable for obtaining an achromatic gray tone. Further, addition of Mg promotes precipitation of Mn, but does not change the form of the precipitate, so that it is suitable for obtaining an achromatic gray color by avoiding a yellowish color tone after anodizing treatment. Furthermore, Mg is Zn
Coexists with and produces MnZn ₂ and contributes to strength improvement. Here, if the amount of Mg is less than 0.5 wt%, the effect of improving the strength cannot be obtained, and further, the effect of promoting the precipitation of Mn and obtaining an achromatic gray color tone after the anodizing treatment cannot be sufficiently obtained. On the other hand, when the amount of Mg exceeds 2.0 wt%, the color tone after anodizing treatment becomes too dark and becomes rather black, and the hot workability deteriorates, especially the productivity of hot extrusion decreases. . Therefore, the amount of Mg is set within the range of 0.5 to 2.0 wt%.

Zn: Zn is an element that coexists with Mg and is effective in improving strength. Here, Zn promotes the precipitation of Mn, but since it does not essentially affect the morphology of the precipitate of Mn, it is possible to improve the strength without affecting the tone of achromatic gray after anodizing. Becomes If the Zn content is less than 1.0 wt%, the effect of improving strength cannot be obtained, while if it exceeds 5.5 wt%, casting becomes difficult, and the hot deformation resistance increases and the hot workability deteriorates.
Was in the range of 1.0 to 5.5 wt%.

Ti, B: These have the effect of refining the crystal grains and preventing the texture and streaks of the rolled sheet. Ti alone or Ti
And B are added in combination. If Ti is less than 0.003 wt%, the above effect cannot be obtained, while if Ti exceeds 0.15 wt%, TiAl ₃
Since coarse intermetallic compounds of
Is in the range of 0.003 to 0.15 wt%. B coexists with Ti and exhibits a refinement effect. When the amount of B added in combination with Ti is less than 1 ppm, the above effect cannot be obtained.
If it exceeds 100 ppm, linear defects due to coarse TiB ₂ particles will occur, so the amount of B should be in the range of 1 to 100 ppm.

In addition to the above elements, basically, Al and other unavoidable impurities may be used. Here, inevitable impurities include Fe, Si, Cr, Cu, Zr, etc.
Since Cr and Cu have some influence on the color tone after anodizing treatment, it is preferable to regulate the amount to a small amount. That is, since Fe changes the color tone from gray to cream depending on the type of intermetallic compound crystallized during casting, if the Fe content is large, segregation during casting may cause a streak pattern. Therefore, it is desirable that the Fe content be less than 0.7 wt%. Moreover, Si promotes the precipitation of Mn.
If a large amount of is included, the type of precipitates tends to be αAlMn (Fe) Si, and in this case, the gray tone becomes lighter and the yellow tint becomes stronger as the color tone after the anodizing treatment. Therefore, it is desirable to control the Si content to less than 0.2 wt%. Further, Cr also changes the color tone after the anodizing treatment, and when the amount of Cr is 0.2 wt% or more, the color tone after the anodizing treatment becomes more yellowish and a coarse intermetallic compound is produced, which is not preferable. So the Cr content is 0.2wt
It is preferable to regulate it to less than%. Cu also changes the color tone after anodizing, and if the Cu content is 0.5 wt% or more, the yellow tint becomes strong and the castability deteriorates. Therefore
It is preferable to regulate the Cu content to less than 0.5 wt%. On the other hand Zr
Has no essential effect on the color tone after anodizing,
If it exceeds 0.3 wt%, a coarse compound may be produced, so Zr is preferably 0.3 wt% or less as an impurity.

Further, generally, in a magnesium-containing aluminum alloy, a small amount of Be is often added to prevent the oxidation of the molten metal, but in the case of the alloy of the present invention, addition of Be does not cause any particular problem. In this case, the amount of Be added is generally 500 ppm or less.

By using an aluminum alloy having the above-described composition, the final wrought material, that is, an extruded shape material or rolled material, is an achromatic color that does not have a yellowish or reddish tint as a color tone after anodizing treatment. You can get a gray tone of.

Next, the method of the invention described in claims 2 and 3, that is, the manufacturing method will be described.

First, a melt of an alloy having the above-described component composition is melted according to a conventional method, and an ingot is formed by a DC casting method (semi-continuous casting method). Then, the ingot is heated at a temperature in the range of 400 ° C to 600 ° C for 0.5 to 24 hours. This ingot heating is not only required for general ingot structure homogenization,
This step is necessary to give an achromatic gray color tone as the color tone after the anodizing treatment. That is, the heating of the ingot promotes the precipitation of Mn-based precipitates such as Al ₆ Mn, Al ₆ (MnFe), and contributes to the development of a neutral gray color after the anodizing treatment by these Mn-based precipitates. . If the ingot heating temperature is less than 400 ° C, the precipitation of Mn-based precipitates is small, and the color tone becomes reddish as the color tone after anodizing treatment.
If it exceeds ℃, there is a risk of eutectic melting. Further, if the ingot heating time is less than 0.5 hours, the above-mentioned effect is not sufficiently obtained, while heating for a long time exceeding 24 hours only causes a decrease in economic efficiency. Therefore, the conditions for heating the ingot were 0.5 to 24 hours at a temperature in the range of 400 to 600 ° C.

After heating the ingot as described above, hot extrusion is applied in the case of the method of the invention of claim 2 to obtain an extruded profile, and hot rolling is applied in the case of the method of the invention of claim 3. Then, if necessary, cold rolling is applied to obtain a rolled material. Therefore, the steps after heating the ingot will be described separately for the case of obtaining an extruded shape and the case of obtaining a rolled material.

A: When obtaining an extruded profile In this case, after heating the ingot under the above conditions,
Although hot extrusion may be carried out immediately, it is common to reheat prior to hot extrusion. For this reheating before hot extrusion, induction heating for a short time is generally applied, but it is appropriate to select a temperature below the ingot heating temperature so as not to affect the color tone after anodizing treatment. is there.

Hot extrusion may be performed according to a conventional method, but the extrusion temperature is
The temperature is preferably 350 to 600 ° C. This hot extrusion plays a role of solutionizing at the same time as extrusion molding, but if the extrusion temperature is less than 350 ° C., the solutionation may be insufficient and finally sufficient strength may not be obtained. Not only is there a possibility that eutectic melting will occur at temperatures above ℃, but coarse recrystallization will occur on the surface of the extruded profile and coarse recrystallization will occur on the surface after anodizing treatment, resulting in a pattern on the surface after anodizing. May occur.

Immediately after hot extrusion, quenching is performed by quenching at a cooling rate of 20 ° C / min or more. That is, so-called die quench is performed. Thus, by rapidly cooling immediately after extrusion, it becomes possible to obtain high strength by aging at room temperature as it is extruded. If this cooling rate is less than 20 ° C / min, a sufficient temperature cannot be obtained,
The cooling rate should be 20 ° C / min or more. However, depending on the component composition of the alloy, it may not be possible to obtain sufficiently high strength with hot extrusion, in which case, for example, 120 ° C x 1
The T5 temper material may be subjected to artificial aging treatment for about 2 hours, or it may be subjected to hot solution extrusion-cooling and then solution treatment-quenching to obtain the T4 temper material or the T6 temper material. The conditions of the solution treatment in this case may be heating at 350 to 600 ° C. × 5 minutes or more as in the case of the solution treatment in a batch type heating furnace for rolled materials described later, and quenching is also performed by the rolling described below. 20 ° C / min as for material
The above cooling rate may be used. The extruded profile obtained as described above may be subsequently subjected to strain correction by stretching.

B: When obtaining a rolled material In this case, after heating the ingot under the conditions as described above,
Immediately hot rolling is performed, or after ingot heating, cooling is performed and then reheating is performed to perform hot rolling. The reheating temperature and the hot rolling temperature are preferably set to a temperature within the range of the aforementioned ingot heating temperature or lower so as not to substantially affect the color tone after the anodizing treatment.

The rolled plate obtained by hot rolling, if the desired final plate thickness is obtained as it is, perform solution treatment-quenching as it is, and if not, subsequently perform cold rolling, After the final plate thickness, solution treatment-quenching is performed. When performing cold rolling, intermediate annealing at 300 to 500 ° C. × 0.5 to 24 hours may be performed between hot rolling and cold rolling or in the middle of cold rolling, if necessary.

The solution treatment temperature is within the range of 350 to 600 ° C. If the solution heat treatment temperature is less than 350 ° C, solution heat treatment will be insufficient and eventually high strength will not be obtained. On the other hand, if it exceeds 600 ° C, eutectic melting may occur, and the color tone after anodizing treatment may be poor. From the viewpoint of stability, the solution treatment temperature is preferably lower than the ingot heating temperature. Here, in the solution treatment-quenching, a batch-type solution heating furnace in which a cut plate is solution-treated and then rapidly cooled may be used, or continuous coiling is performed by continuously passing the coil back through the furnace. A solution hardening quenching furnace or a continuous annealing furnace may be used. Further, in this solution treatment, it is sufficient that the temperature of the material reaches the temperature within the range of 350 to 600 ° C. described above, and it is not necessary to take a holding time, but from the viewpoint of improving the quality stability, In the case of a batch type heating furnace, it is desirable to hold it for 5 minutes or longer, and in the case of a continuous furnace, it is desirable to hold it for 10 seconds or longer. Quenching after the solution treatment requires a cooling rate of 20 ° C / min or more. If the cooling rate is 20 ° C / min, the effect of quenching is insufficient, and finally high enough strength cannot be obtained.

In the case of a cut plate, the rolled plate manufactured as described above is usually strain-corrected by a single plate leveler, stretch or the like, if necessary. Further, in the case of a coil, if higher strength is required, cold rolling may be further performed. In any case, after that, leveling as a coil or stretch after cutting is performed for straightening the strain. It is normal. Furthermore, for strength improvement, for example, 120
You may give artificial aging treatment of about 12 hours at ℃.

As described above, the extruded shape material obtained in the step A or the rolled material obtained in the step B is anodized to obtain a gray color which is not yellowed or reddish,
That is, it is possible to stably obtain an achromatic gray tone.

Next, for the extruded shape material or rolled material as described above,
A process for performing anodizing treatment to actually obtain an achromatic gray tone will be described.

In the anodic oxidation treatment, degreasing and etching are generally performed in order to remove surface stains and surface defects in advance. The etching is usually a caustic soda-based alkali etching. And for the anodizing treatment itself, a sulfuric acid bath with a H ₂ SO ₄ concentration of 10 to 25 vol% is used, the bath temperature is 10 to 30 ° C., the current density is 1.5 A / dm ² or more and 2.5 A / d.
It is performed under m ² to form an anodized film with a thickness of 10 to 30 μm.

Here, when the H ₂ SO ₄ concentration of the sulfuric acid bath is less than 10 vol%, the porosity of the anodic oxide film formed is reduced and the bath voltage is increased. On the other hand, when the H ₂ SO ₄ concentration exceeds 25 vol%, the surface becomes rough and the anodic oxide film becomes soft. If the bath temperature is less than 10 ° C, it takes a long time to obtain the required film thickness, which is uneconomical. On the other hand, if the bath temperature exceeds 30 ° C, the corrosion resistance after anodizing is deteriorated. Furthermore, if the current density is 2.5 A / dm ² or more, a large amount of power is required for the treatment, which is not practical, while if it is less than 1.5 A / dm ² , the color tone after anodizing treatment becomes light and gray cannot be obtained. Also, the thickness of the anodic oxide film formed is 10μ.
If it is less than m, sufficient corrosion resistance cannot be obtained, while it is not economical to increase the thickness to more than 30 μm.

By the anodizing treatment with the sulfuric acid bath as described above, an achromatic gray color tone can be obtained. For the color tone after the anodizing treatment, refer to the Hunter color difference formula (JIS Z
8730), the lightness index L and the chromaticness index a,
It can be evaluated by the value of b. That is, the higher the L value of the lightness index is, the whiter it is, while the chromaticness index is about the coloring degree, the higher the a value is, the stronger the reddish color is, and the higher the b value is, the stronger the yellowish color is.
And the achromatic gray tone that is the objective of this invention is
L value, a value, b value can be defined as a color tone that satisfies 40 <L <65, -2 <a <+2, -2 <b <+2, and a more desirable L value range is 45 <L. <65.

Example [Example 1] The molten alloy Nos. 1 to 5 shown in Table 1 were melted according to a conventional method, and 450 mm x 120 by a semi-continuous casting method (DC casting method).
A 0 mm x 4000 mm slab was cast. After chamfering each of the obtained slabs, ingot heating was performed under various conditions as shown in Condition Nos. 1 to 6 in Table 2, and hot rolling was started at the temperature shown in Table 2 as well. A hot rolled sheet having a sheet thickness of 4 mm was used. Then, it was cold-rolled to a plate thickness of 2 mm. Then, solution annealing and quenching were performed in a continuous annealing furnace. The conditions for solution treatment are 50
Hold at 0 ℃ × 10sec, quenching is 30 ℃ / sec by forced air cooling
Cooling rate. Then, after leveling, it cut | disconnected and flattened by the stretch.

Then, each plate was etched with a 10% NaOH aqueous solution, washed with water, and then desmutted with nitric acid. Then H ₂
Use a sulfuric acid bath with SO ₄ concentration of 15 vol%, bath temperature 20 ℃, current density
Anodizing at 1.5 A / dm ² and film thickness of 20 μm each
Of the anodic oxide film was generated.

The surface color tone of the anodized film of each plate was examined using a color meter SM-3-MCH manufactured by Suga Test Instruments. The color tone was evaluated using the lightness index L and the chromaticness index a and b according to Hunter's color difference formula. The results are shown in Table 3. The strength (tensile strength and proof stress) of each plate was examined, and the results are also shown in Table 3.

As is clear from Table 3, for alloys No. 1 and No. 2 within the compositional range of the present invention, the process conditions of the present invention
It was found that the rolled plates manufactured according to No. 1 and No. 2 all had an achromatic gray color after anodizing and had high strength.

Example 2 A molten alloy No. 6 shown in Table 4 was melted according to a conventional method,
It was cast into a billet having a diameter of 8 inches by a semi-continuous casting method (DC casting method). About the obtained billet, 550 ℃ × 1
After heating the ingot for 0 hours, hot extrusion was performed at 500 ° C. to extrude a plate having a cross-sectional dimension of 3 mm × 50 mm, forced air cooling immediately after the extrusion, and rapid cooling at a cooling rate of 30 ° C./sec. The extruded plate thus obtained was subjected to etching with 10% NaOH, washing with water and desmutting with nitric acid as in Example 1, and further anodizing under the same conditions as in Example 1 to examine the color tone and strength. Table 5 shows the results.

As is clear from Table 5, even in the case of an extruded material, it was found that by satisfying the conditions of the present invention, an achromatic gray tone and high strength can be obtained after anodizing treatment.

EFFECTS OF THE INVENTION As is clear from the above examples, the aluminum alloy wrought product of the invention of claim 1 stabilizes the color tone of gray without yellowish or reddish, that is, achromatic gray by the anodizing treatment. It has a high strength. Further, according to the methods of claims 2 and 3, it is easy to actually produce an aluminum alloy extruded shape material or rolled material having an achromatic gray color tone and high strength after anodizing treatment on a mass-production scale. Can be manufactured.

Claims (3)

(57) [Claims] 1. Mn 0.5 to 2.0 wt%, Mg 0.5 to 2.0 wt%, Zn
It contains 1.0 to 5.5 wt% and Ti as a grain refiner.
A high-strength aluminum alloy with a gray tone after anodization characterized by containing 0.003 to 0.15 wt% alone or in combination with B 1 to 100 ppm, the balance being Al and other unavoidable impurities. Drawn material. 2. Mn 0.5 to 2.0 wt%, Mg 0.5 to 2.0 wt%, Zn
It contains 1.0 to 5.5 wt% and Ti as a grain refiner.
An alloy containing 0.003 to 0.15 wt% alone or in combination with B 1 to 100 ppm, with the balance being Al and other unavoidable impurities, cast by DC casting method, then 400-600 ° C against the ingot After the anodizing treatment, which is characterized by performing a treatment of heating at a temperature within the range of 0.5 to 24 hours, followed by hot extrusion and cooling immediately after the hot extrusion at a cooling rate of 20 ° C / min or more. Of high strength aluminum alloy wrought material with a gray color tone. 3. Mn 0.5 to 2.0 wt%, Mg 0.5 to 2.0 wt%, Zn
It contains 1.0 to 5.5 wt% and Ti as a grain refiner.
An alloy containing 0.003 to 0.15 wt% alone or in combination with B 1 to 100 ppm, with the balance being Al and other unavoidable impurities, cast by DC casting method, then 400-600 ° C against the ingot Heat treatment at a temperature within the range of 0.5 to 24 hours, then hot rolling, or hot rolling and cold rolling, and after hot rolling or cold rolling 350
A method for producing a high-strength aluminum alloy wrought material having a gray tone after anodizing, characterized by heating to a temperature in the range of to 600 ° C and cooling at a cooling rate of 20 ° C / min or more.