JPH0445241A - High strength aluminum alloy elongating material having gray color tone after anodic oxidation treatment and its manufacture - Google Patents

Abstract

PURPOSE:To stably manufacture a high strength Al alloy elongating material having a gray color tone after anodic oxidation treatment by subjecting a DC cast ingot having a specified compsn. constituted of Mn, Mg, Zn, Ti, B and Al to specified heat treatment and thereafter executing hot extruding and cooling. CONSTITUTION:An alloy contg., by weight, 0.5 to 2.0% Mn, 0.5 to 2.0% Mg and 1.0 to 5.5% Zn, furthermore contg., as a crystal refining agent, independently, 0.003 to 0.15% Ti or in combination with 1 to 100ppm B and the balance Al with other inevitable impurities is cast by a DC casting method. This ingot is subjected to heating treatment at 400 to 600 deg.C for 0.5 to 24hr. After that, the ingot is subjected to hot extruding or hot rolling and, if required, cold rolling. The sheet immediately after the above extruding or the rolled sheet is heated to 350 to 600 deg.C and is thereafter cooled at >=20 deg.C/min. In this way, the Al alloy elongating material stably obtainable an achromatic gray color tone as the color tone after anodic oxidation treatment and having sufficient strength can easily be obtd.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention relates to high-strength aluminum alloy wrought materials that are used after anodizing treatment, particularly building materials such as curtain walls of buildings, architectural exterior materials, and interior materials; The present invention also relates to a high-strength aluminum alloy wrought material used as an extruded or rolled material for utensils, containers, electrical measuring equipment casings, nameplates, etc., and a method for producing the same.

Conventional technology Aluminum alloy wrought materials, extruded shapes and rolled materials, are generally used for building materials such as curtain walls, building exterior materials, and interior materials, as well as for vessels, containers, electrical measuring equipment casings, nameplates, etc. From the viewpoint of corrosion resistance, it is often used after being anodized. Aluminum alloys for anodizing treatment for these purposes often have a color tone from light gray to silver after anodizing treatment, and rolled materials of such alloys are generally JI51050 alloy, 11 (1
0 alloy, 5005 alloy, etc. are often used (Also, 6063 alloy etc. are often used for extruded shapes, such as sashes.Also, as grayish materials, Al- 1 to 4% Si alloy is common.In addition, aluminum alloys with gray color after anodizing treatment include A7-Fe alloy and A I-F alloy.
E-Mg-Mn alloys have been proposed. As the anodizing method, anodizing using a sulfuric acid electrolytic bath has been commonly used from the viewpoint of economy and corrosion resistance.

Problems to be Solved by the Invention Among various color tones, gray tones are often required for applications such as building materials because they give a calming texture.

However, the A7-8i series aluminum alloy has poor desmut properties, and the surface becomes powdery after anodizing treatment, and the color tone after anodizing treatment is yellowish or gray, although it is grayish. It has a strong red tinge, and a lighter achromatic gray color is often desired.

On the other hand, Al-Fe alloys and A I-Fe e-M g −
Mn-based alloys can compensate for the drawbacks of Al-5i-based alloys as mentioned above, but they cannot be used as extruded shapes such as sashes due to insufficient strength, and they do not have high strength as rolled materials. There is a problem that it is inappropriate when required.

This invention was made against the background of the above-mentioned circumstances, and it is possible to stably obtain a gray tone that is not yellowish or reddish, that is, an achromatic gray tone after anodizing treatment. The object of the present invention is to provide a wrought aluminum alloy material having sufficiently high strength and a method for producing the same.

Means for Solving the Problems The inventors of the present invention have repeatedly conducted various experiments and studies on means for solving the above-mentioned problems, and found that Mn
It was discovered that by controlling the precipitates, it was possible to make the anodic oxide film achromatic gray and at the same time obtain high strength, and this invention was accomplished.

Specifically, the aluminum alloy wrought material of the invention of claim 1 contains Mn 0.5 to 2.0 wt%, Mg 0.5 to 2,
0 wt%, Zn 1.0 to 5.5 vf%, and Ti 0.003 to 0.15 wt as a grain refiner.
% alone or in combination with Bl~I (loppm), and the remainder consists of Al and other unavoidable impurities, and by having such a component composition, anodizing It has become possible to obtain an achromatic gray color tone after treatment, and also to obtain high strength.

The invention of claim 2 is directed to a method for manufacturing an extruded shape material among wrought materials, and after casting the alloy having the same composition by a DC casting method, the ingot is
heating to a temperature within the range of ~600°C for 0.5 to 24 hours,
After that, hot extrusion is performed, and immediately after the hot extrusion, 20℃/
By cooling at a cooling rate of min. or more, an aluminum alloy extruded shape having an achromatic gray color after anodizing treatment and high strength is obtained.

Furthermore, the invention of claim 3 relates to a method for manufacturing a rolled material among the wrought materials, and after casting the alloy having the same composition by a DC casting method, the ingot is
Heating at a temperature within the range of 600°C for 0.5 to 24 hours, followed by hot rolling, or hot rolling and cold rolling, to a temperature of 350 to 600°C after hot rolling or after cold rolling.
By heating to a temperature change within the range of 0°C and cooling at a cooling rate of 20°C/min or more, a rolled material having an achromatic gray color after anodizing treatment and high strength is obtained.

Function First, the reason for limiting the composition of the aluminum alloy wrought material of the present invention will be explained.

Mn: Mn is an important element for forming A7-Mn-based intermetallic compounds and determining the color tone after anodizing treatment. /Mn
5iSAA'MnFe.

It has been found that the type and size of the anodic oxide film (AIM n F e Cr, etc.) are important in making the color tone of the anodic oxide film achromatic gray. That is, when Mn coexists with Mg, precipitation of Mn-based precipitates of a predetermined size is achieved, and the anodic oxide film becomes grayish in color.

If the Mn amount is less than 0.5vj%, sufficient graying will not be achieved, while if the Mn amount is less than 2.5vj%. If Qvt% is exceeded, graying is possible, but primary intermetallic compounds are generated during DC casting. Therefore, the Mn content was limited to a range of 0.05 to 2.011%.

Mg: Mg is an element necessary to promote the precipitation of Mn and generate Mn-based precipitates of a predetermined size.

In particular, the cooling rate during casting is slow compared to continuous thin plate casting such as DC casting (and when the amount of forced solid solution of Mn is small,
Unless a certain amount of Mg is contained, the size of the Mn-based precipitates will not be suitable for obtaining an achromatic gray tone after anodizing treatment.

Furthermore, although the addition of Mg promotes the precipitation of Mn, it does not change the form of the precipitates, so it is ideal for avoiding yellowing of the color tone after anodizing treatment and obtaining an achromatic gray color.

Furthermore, Mg coexists with Zn to generate MnZn2, which contributes to improving the strength. Here, if the amount of Mg is less than 0.5 vt%, the effect of improving strength cannot be obtained, and furthermore, the effect of promoting precipitation of Mn and obtaining an achromatic gray tone after anodizing treatment cannot be sufficiently obtained. On the other hand, if the Mg content exceeds 2011%, the color tone after the anodizing treatment becomes too dark and becomes black, and hot workability deteriorates, particularly productivity in hot extrusion. Therefore, the amount of Mg is 0.5 to 2
．． It was set within the range of 0 wt%.

z n : 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 form of the precipitates, it is possible to improve the strength without affecting the achromatic gray tone after the anodizing treatment.

If the amount of Zn is less than 0 wt%, the effect of improving strength cannot be obtained, while if it exceeds 5 wt%, casting becomes difficult, hot deformation resistance increases, and hot workability deteriorates. was within the range of 1.0 to 5.5 wf%.

Ti, B: These have the effect of refining the crystal grains and preventing the texture and streaks of the rolled plate.
Add i and B in combination. Ti is 0. QQ3wt%
If the Ti is less than 0.15wt, the above effect cannot be obtained.
%, there is a risk that a coarse intermetallic compound of TiAl3 will be formed, so Ti is 0.003 to 0.15wt.
Within the range of %. B coexists with Ti and exhibits a refinement effect. If the amount of B added in combination with Ti is less than ippm, the above effects cannot be obtained;
If it exceeds ppm, linear defects will occur due to coarse TiB2 particles, so the amount of B should be within the range of 1 to 100 ppm.

In addition to the above-mentioned elements, basically Al and other unavoidable impurities may be used. Here, unavoidable impurities include Fe, Si, Cr, and Cu.

Among them, Fe, Si, and Cr.

Since Cu has a certain degree of influence on the color tone after anodizing treatment, it is preferable to limit it to a small amount. That is, since Fe changes the color tone from gray to cream depending on the type of intermetallic compound that crystallizes during casting, if the amount of Fe is large, there is a risk that a streak pattern may occur due to segregation during casting. Therefore, it is desirable that the amount of Fe be less than 0.7 wt%. In addition, Sl promotes the precipitation of Mn, but if a large amount of Si is contained, the type of precipitates will be a
AlMn (F e) Si easily becomes AlMn (Fe) Si (in this case, the color tone after anodizing treatment becomes lighter gray and more yellowish. Therefore, it is desirable to regulate the amount of St to less than 0.2 wt%. Furthermore, Cr It changes the color tone after anodizing treatment, and if the Cr amount is 0.2vj% or more, the color tone after anodizing treatment will have a strong yellowish tinge, and coarse intermetallic compounds will be generated, which is not preferable. 0.2wt%
It is preferable to limit the amount to less than Further, Cu also changes the color tone after anodizing treatment, and if the amount of Cu is 0.5 vt% or more, the yellowish tinge becomes strong and the castability deteriorates.

Therefore, it is preferable to restrict the amount of Cu to less than Q, 5 wt%. On the other hand, Zr has no essential effect on the color tone after anodizing treatment, but if it exceeds 0.3 wt%, coarse compounds may be generated.
The content is preferably 3 wt% or less.

In general, in aluminum alloys containing Mg, a trace amount of Be is often added to prevent oxidation of the molten metal, but there is no particular problem in adding Be to the alloy of the present invention. In this case, the amount of Be added is 500p
pm or less is common.

By making an aluminum alloy with the above-mentioned composition, the color tone after anodizing the final drawn material, i.e., the extruded shape material or the rolled material, is an achromatic color that is not yellowish or reddish. gray tones can be obtained.

Next, the method of the invention according to claims 2 and 3, ie, the manufacturing method, will be described.

First, a molten alloy having the above-mentioned composition is melted according to a conventional method, and an ingot is formed by a DC casting method (semi-continuous casting method). Next, the ingot is heated at a temperature in the range of 400 to 600°C for 0.5 to 24 hours. This ingot heating is not only necessary for homogenizing the ingot structure, but also is a necessary step to give the ingot an achromatic gray tone after the anodizing treatment. That is, by heating the ingot, Al6Mn, which is a Mn-based precipitate, is formed.

It promotes the precipitation of A I a (Mn Fe) and the like, and contributes to the achromatic gray coloring after the anodization treatment due to these Mn-based precipitates. When the ingot heating temperature is less than 400°C, there is little precipitation of Mn-based precipitates, resulting in a reddish color tone after anodizing treatment, while at 600°C
If it exceeds this, there is a risk of eutectic melting. Further, if the ingot heating time is less than 0.5 hours, the above-mentioned effects cannot be 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 are 400 to 6
The temperature was within the range of 0.000C for 0.5 to 24 hours.

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

A: When obtaining an extruded shape In this case, hot extrusion may be performed immediately after heating the ingot under the conditions described above, but it is usually best to reheat it prior to hot extrusion. Common. For this reheating before hot extrusion, short-time induction heating is generally applied.
It is appropriate to select a temperature equal to or lower than the ingot heating temperature so as not to affect the color tone after anodizing treatment.

Hot extrusion can be carried out according to conventional methods, but the extrusion temperature
It is preferable to set it as 350-600 degreeC. This hot extrusion plays the role of solution treatment at the same time as extrusion molding.
If the extrusion temperature is less than 350°C, there is a risk that foaming will be insufficient and sufficient strength will not be obtained in the end, while at a high temperature exceeding 600°C, there is a risk of eutectic melting and the extrusion There is a risk that coarse recrystallization will occur on the surface of the profile, and that coarse recrystallization will occur on the surface after the anodization treatment, resulting in a pattern on the surface after the anodization treatment.

Immediately after hot extrusion, quenching is performed by rapidly cooling at a cooling rate of 20°C/min or more. That is, so-called die quenching is performed. By rapidly cooling the material immediately after extrusion in this manner, it is possible to obtain high strength by aging at room temperature as extruded. If the cooling rate is less than 20°C/min, a sufficient temperature cannot be obtained, so the cooling rate must be 20°C/min or more. However, depending on the composition of the alloy, it may not be possible to obtain sufficient high strength by hot extrusion, and in that case, it may be made into a T5 tempered material by applying an artificial aging treatment of, for example, 120'CX for about 12 hours. Alternatively, hot extrusion - solution treatment again after cooling - quenching is applied
4 temper material or T6 temper material may be used. The conditions for the solution treatment in this case are the same as those for the solution treatment using a batch heating furnace for rolled materials, which will be described later.
0~b Good, and quenching is also done at 20℃ as in the case of rolled material described later.
It is sufficient to set the cooling rate to 100% or more. Note that the extruded shape obtained as described above may be subsequently subjected to distortion correction by stretching.

B: When obtaining a rolled material In this case, after heating the ingot under the conditions described above, hot rolling is performed immediately, or after heating the ingot, it is cooled once and then reheated and then hot rolled. Do this. The reheating temperature and hot rolling temperature are preferably within the range of the above-mentioned ingot heating temperature or lower so as not to essentially affect the color tone after anodizing treatment.

The rolled plate obtained by hot rolling is subjected to solution treatment and quenching as it is if the desired final plate thickness is obtained, and if not, it is subsequently cold rolled. After achieving the final plate thickness, solution treatment and quenching are performed. When cold rolling is carried out, it may be 300-b between hot rolling and cold rolling or in the middle of cold rolling, if necessary.

The temperature of the solution treatment is within the range of 350 to 600°C.

If the solution treatment temperature is less than 350℃, the solution treatment will be insufficient and ultimately sufficient high strength will not be obtained.On the other hand, if it exceeds 600℃, there is a risk of eutectic melting, and the color tone after anodizing treatment will change. Also from the viewpoint of stability, the solution treatment temperature is preferably lower than the ingot heating temperature. Here, for the solution treatment and quenching, a batch type solution heating furnace may be used in which the cut plate is solution treated and then rapidly cooled, or a continuous process in which the coil is passed through the furnace while being continuously unwound. A solution hardening furnace or a continuous annealing furnace may also be used.

In addition, in this solution treatment, the temperature of the material is
It is sufficient to reach a temperature within the range of 50 to 600°C, and there is no need to take a particular holding time; however, from the perspective of improving the stability of Shinaga, in the case of a batch-type heating furnace, it should be held for at least 5 minutes. In the case of a continuous furnace, it is desirable to hold the temperature for 10 seconds or more. Quenching after solution treatment is 20℃/min.
A cooling rate higher than that is required. If the cooling rate is 20° C./immediately, the quenching effect will be insufficient and ultimately sufficient high strength will not be obtained.

In the case of a cut plate, the rolled plate produced as described above is usually straightened for distortion using a veneer leveler, stretching, etc., as necessary. In the case of coils, if higher strength is required, further cold rolling may be performed.
In any case, the coil is usually leveled or stretched after cutting to correct distortion. Furthermore, in order to improve the strength,
An artificial aging treatment for about 12 hours may also be applied.

As described above, the extruded shape obtained by step A or the rolled material obtained by step B is anodized to produce a gray color without yellowness or reddishness, that is, an achromatic gray color. A stable color tone can be obtained.

Next, a process for actually obtaining an achromatic gray tone by anodizing the extruded or rolled material as described above will be explained.

Before anodizing, degreasing and etching are generally performed to remove surface stains and surface defects in advance. Etching is usually performed using caustic soda-based alkaline etching. In the anodizing process itself, the H2SO4 concentration is 10 to 25 voJ.
% sulfuric acid bath, bath temperature 10-30°C, current density 1.
5A #n1 or more and less than 2.5A/-, film thickness 1
Generate an anodized film of G~30LLI11.

Here, if the H2SO4 concentration of the sulfuric acid bath is less than 10 vol%, the porosity of the anodic oxide film produced will decrease and the bath voltage will increase. On the other hand, if the H2So concentration exceeds 25 m%, the surface becomes rough and the anodic oxide film becomes soft. Furthermore, if the bath temperature is below 1.theta..degree. C., a long treatment time is required to obtain the required film thickness, which is uneconomical.If the bath temperature exceeds 30.degree. C., the corrosion resistance after the anodizing treatment will deteriorate. Furthermore, the current density is 2
．． 5A/dff! The above treatment requires a large amount of power and is not practical, and if it is less than 1.5 A/(hd), the color tone after the anodizing treatment becomes pale and gray cannot be obtained. If the film thickness is less than 10 ua, sufficient corrosion resistance cannot be obtained, and on the other hand, increasing the film thickness to more than 3G+, tm is not economical.

An achromatic gray tone can be obtained by the anodic oxidation treatment using a sulfuric acid bath as described above. Regarding the color tone after anodizing treatment, please refer to )1-inter color difference formula (JIS
0730) and the chromaticness index a and b. That is, the higher the L value of the lightness index, the whiter it is, while the Romanticness index is about the degree of coloration, and the higher the a value, the stronger the redness, and the higher the b value, the stronger the yellowness. The achromatic gray tone targeted by this invention has the following values: 4G<L<65, -2<a<+2, -2<b<+2
A more desirable range of L values is 45<L<65.

Example [Example 1] The molten metal of alloy N11l~5 shown in Table 1 was melted according to a conventional method, and 450
A slab of w x 1200w x 4G00m was cast.

For each slab obtained, after the surface side, the conditions listed in Table 2 are as follows:
The ingots were heated under various conditions as shown in Table 6, and hot rolling was started at the temperatures shown in Table 2 to obtain hot rolled sheets with a thickness of 4 m. Then, it was cold rolled to a plate thickness of 2 m. Thereafter, solution treatment and quenching were performed in a continuous annealing furnace. The conditions for the solution treatment were 500°C XIQsec holding, and the quenching was performed by forced air cooling at a cooling rate of 30°C/sec.

Thereafter, it was leveled, cut, and flattened by stretching.

Thereafter, each plate was etched with a 10% NaOH aqueous solution, washed with water, and then desmutted with nitric acid. Next, using a sulfuric acid bath with a H2SO4 concentration of 15vo/%, the bath temperature was 2.
0℃, current density 1.5A/do! An anodic oxidation treatment was carried out to form an anodic oxide film having a film thickness of 2oLLffl.

The surface color tone of the anodic oxide film of each board was examined using Colormeter SM-3-MCI (manufactured by Suga Test Instruments).

The color tone was evaluated using the brightness index and 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 also investigated and the results are also shown in Table 3.

As is clear from Table 1 and Table 3, for the alloys N11l and Nα2 within the composition range of the present invention, the rolled plates manufactured according to the process conditions Arashi 1 and NCL2 of the present invention were all treated after anodizing treatment. The color tone is achromatic gray,
Moreover, it was found to have high strength.

[Example 2] A molten metal of Alloy Ma 6 shown in Table 4 was melted according to a conventional method, and cast into a billet with a diameter of 8 inches by a semi-continuous casting method (DC casting method). For the obtained billet, 550°C
After heating the ingot for 10 hours, hot extrusion was carried out at 500°C to extrude a plate with cross-sectional dimensions of 3w x 50mm, and immediately after extrusion, forced air cooling was performed to rapidly cool the ingot at a cooling rate of 30°C/see. Regarding the obtained extruded plate, 10
% NaOH, washing with water, desmutting with nitric acid, and then anodizing under the same conditions as in Example 1 to examine the color tone and strength. The results are shown in Table 5.

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

Effects of the Invention As is clear from the above examples, the aluminum alloy wrought material of the invention of claim 1 has a stable gray tone that is not yellowish or reddish, that is, an achromatic gray color, by anodizing treatment. and has high strength. Furthermore, according to the methods of claims 2 and 3, it is possible to easily produce aluminum alloy extruded shapes or rolled materials on a mass-produced scale that exhibit an achromatic gray tone and have high strength after anodizing treatment as described above. can be manufactured.

Applicant Sky Aluminum Co., Ltd. Agent Patent Attorney Yutaka 1) Hisashi Take

Claims (3)

[Claims] (1) Mn0.5-2.0wt%, Mg0.5-2.0
wt%, Zn 1.0 to 5.5 wt%, and Ti 0.003 to 0.15 wt% as a grain refiner alone or in combination with B1 to 100 ppm, the balance being Al and other A high-strength aluminum alloy wrought material that is gray in color after being anodized and is characterized by containing unavoidable impurities. (2) Mn0.5-2.0wt%, Mg0.5-2.0
wt%, Zn 1.0 to 5.5 wt%, and Ti 0.003 to 0.15 wt% as a grain refiner alone or in combination with B1 to 100 ppm, the balance being Al and other After casting an alloy containing unavoidable impurities by the DC casting method, the ingot is
It is characterized by performing a heating treatment at a temperature within the range of ~600°C for 0.5 to 24 hours, then performing hot extrusion, and immediately after the hot extrusion, cooling at a cooling rate of 20°C/min or more. , a method for producing a high-strength wrought aluminum alloy material that is gray in color after anodizing treatment. (3) Mn0.5-2.0wt%, Mg0.5-2.0
wt%, Zn 1.0 to 5.5 wt%, and Ti 0.003 to 0.15 wt% as a grain refiner alone or in combination with B1 to 100 ppm, the balance being Al and other After casting an alloy containing unavoidable impurities by the DC casting method, the ingot is
A heating treatment is performed at a temperature in the range of ~600°C for 0.5 to 24 hours, and then hot rolling or hot rolling and cold rolling is performed, and after hot rolling or cold rolling, 3
Heating to a temperature within the range of 50 to 600°C at 20°C/mi
A method for producing a high-strength aluminum alloy wrought material having a gray color after anodizing treatment, characterized by cooling at a cooling rate of n or more.