JPH03130341A - Aluminum alloy sheet coloring into light gray color and its production - Google Patents

Abstract

PURPOSE:To produce an Al alloy sheet coloring into a light gray color by means of anodic oxidation treatment using sulfuric acid bath by specifying annealing time at the time of forming an ingot of an Al alloy containing specific percentages of Si, Fe, and Cu into the prescribed sheet thickness. CONSTITUTION:An ingot of an Al alloy having a composition consisting of, by weight, 0.3-3.0% Si, 0.1-1.0% Fe, <=0.2% Cu, and the balance Al with inevitable impurities is subjected to homogenizing treatment and to hot rolling. Subsequently, at the time of forming the above ingot into the prescribed sheet thickness by means of cold rolling and process annealing or final annealing, annealing temp. is controlled to 380-450 deg.C, and also annealing time is regulated to >= about 30min. By this method, the Al alloy sheet coloring into a self-color light gray in the range of about 10-30mu film thickness in anodic oxidation treatment by means of a sulfuric acid bath can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a naturally colored aluminum alloy plate exhibiting a light gray color used for building materials, etc., and a method for manufacturing the same. In sulfuric acid bath anodizing treatment, 1 ton of skin! The present invention relates to an aluminum alloy plate that develops a light gray color in a J thickness range of 10 to 30μ, and a method for manufacturing the same.

[Conventional technology and its issues]

Conventional gray naturally colored An alloys include A/! containing approximately 5% Si. -3i series (7) JIS4043 alloy is anodized in a sulfuric acid bath and is widely used for exterior and interior materials of buildings, automobile parts, appliances, electrical products, etc., but the color tone of this alloy is , for example, film thickness 2
At 0μ, it is usually a dark gray to dark gray, and if a light gray tone is required, a thin anodic oxide film (less than 10μ) can be formed, since the film is thin. There is a problem in that the inherent advantages of the anodized film, such as corrosion resistance, weather resistance, and abrasion resistance, are impaired.

[Means and effects for solving the problem] In view of the above situation, the present invention has conducted extensive research, and has developed
has a low composition, and Fe.

It was discovered that when Cu is limited to a predetermined amount and annealed at a relatively high temperature and then anodized, it develops a light gray color even if a thick oxide film (10 to 30μ) is formed. This led to the completion of the present invention.

In addition, in this specification, a light color (light dull color) is a color tone with an L value (lightness) of 50 to 50 according to the Hunter color display method.
75, the a value (green to red) is in the range of -2 to +2, and the b value (blue to yellow) is in the range of -2 to +2.

The invention of claim 1 is characterized in that the silicon content is 0.3 to 3. Qwt%, iron 0
．． 1 to 1, containing 1t% of Qi and 0.2wt% or less of copper,
This is an aluminum alloy plate that develops a light gray color and is characterized in that the remainder consists of aluminum and unavoidable impurities.

The alloy plate of the present invention undergoes anodizing treatment using a sulfuric acid bath.
The film thickness is 10, which is necessary to maintain corrosion resistance and wear resistance.
- From the above thickness, 30I is considered to be the upper limit from an economic point of view!
It exhibits a moderate light gray color within the thickness range of ta,
The mechanical properties are equivalent to JISI 100 alloy, making it an extremely useful alloy plate as a building material.

In the alloy plate of the present invention, Si has the effect of coloring the film pale gray, and the reason for limiting its content to 0.3 to 3.0 wt% (hereinafter -t% is simply abbreviated as %) is as follows: .3%
If it is less than 3.0%, light gray color will not be developed sufficiently, and if it exceeds 3.0%, it will become gray and the color will be too dark. Also Fe
and Cu are added to impart mechanical properties equivalent to those of the JIS 1100 alloy and to adjust color tone. That is, Fe has the effect of increasing strength and toughness, and the reason why its content was limited to 0.1 to 1.0% is because
If it is less than 0.1%, its effect will not be fully expressed;
This is because the color tone becomes yellowish when it exceeds this range. Further, Cu has the effect of increasing strength, and the reason why its content is limited to 0.2% or less is that if it exceeds 0.2%, the color tone becomes yellowish.

The invention of claim 2 is characterized in that the silicon content is 0.3 to 3.0% and the iron content is 0.1%.
An aluminum alloy ingot containing up to 1.0% and 10.2%, with the remainder consisting of aluminum and unavoidable impurities, is homogenized and then hot rolled, followed by cold rolling and intermediate annealing or This is a method for manufacturing an aluminum alloy plate that develops a light gray color, characterized in that the annealing conditions are set at 380 to 450°C when final annealing is performed to obtain a predetermined thickness, if necessary.

The method for manufacturing the alloy plate of the present invention includes, for example, melting an alloy of a predetermined composition, casting it into an ingot for rolling, and then subjecting it to surface separation, homogenization treatment, hot rolling, cold rolling, intermediate annealing, finish rolling or When each step of final annealing is performed sequentially as necessary to obtain a plate material of a predetermined thickness, the intermediate or final annealing conditions are set to 380 to 450°.
C. This plate material is anodized in a sulfuric acid bath to develop a pale gray color with a coating thickness in the range of 10 to 30 microns before use. In the above, the final tempering of the plate is
Depending on the purpose, there are cold rolled plates (Hl, material) by finish rolling and annealed plates (0 material) by final annealing.

In the method of the present invention, Si remains as a precipitate in the film and has the effect of causing the film to develop a light gray color, but when the precipitate becomes fine, the color becomes yellowish. Therefore, in the method of the present invention, the annealing temperature is set to 3.
The reason for limiting the temperature to 80 to 450'C is that if it is less than 380°C, Si will precipitate finely and the color will be yellowish, and if it exceeds 450°C, it will not only be a waste of energy but also This is because crystal grains tend to become coarser and mechanical properties deteriorate. Further, the annealing time is preferably 30 minutes or more in order to reliably suppress fine precipitation of St.

The anodizing treatment of the colored aluminum alloy plate according to the present invention is mainly carried out using a sulfuric acid bath, and general conditions such as concentration, temperature, current density, etc. are usually applied.

〔Example〕

Examples of the present invention will be described in detail below.

Al1-3 i -F e-C of various m precepts shown in Table 1
The U-based alloy was melted and cast into a rolling ingot, and this ingot was face-divided, homogenized at 550°C for 5 hours, then hot rolled at 500°C, and then cold rolled. Inter-rolling was performed to obtain a plate material with a thickness of 4 II m. This plate material was intermediately annealed for 30 minutes at various temperatures, and then finished cold rolled to a thickness of 2 mm to obtain a semi-hard material.

These plates were anodized under the same conditions,
Next, after washing with water, the plate was immersed in boiling water for 20 minutes to seal the pores to produce a naturally colored plate. The above anodic oxidation treatment was carried out using a sulfuric acid bath with a sulfuric acid concentration of 15%, a bath temperature of 20''C2 current density], and a direct current of 2 A/d- applied.

The film thickness and color tone of each of the naturally colored plates thus obtained were examined. The survey results are also listed in Table 1.

As is clear from Table 1, the invention examples (Nos. 1 to 7) are:
The L value of the Hunter color display method at a film thickness of 20-
It can be seen that the a value and b value develop into a light gray color, which is the objective of the present invention.

On the other hand, in Comparative Example No. 8, the gray color was not sufficiently developed due to the small amount of Si, and on the contrary, the color of No. 9 was gray and dark due to too much Si. In addition, Nos. 10 to 12 all had a yellowish tinge, but this was due to the annealing temperature, Fe content, Cu
This is because the respective contents are outside the scope of the present invention.

〔effect〕

As described above, according to the present invention, an AN alloy sheet that naturally develops a light gray color within a film thickness of 10 to 30 μm can be obtained through anodizing treatment using a sulfuric acid bath, meeting various needs as a building material, etc. It can be achieved and has remarkable industrial effects.

Claims (2)

[Claims] (1) Silicon 0.3-3.0wt%, iron 0.1-1.0w
A pale gray colored aluminum alloy plate containing 0.2 wt% or less of copper, and the remainder consisting of aluminum and unavoidable impurities. (2) Silicon 0.3-3.0wt%, iron 0.1-1.0w
t%, copper 0.2wt% or less, and the balance consists of aluminum and unavoidable impurities,
After homogenization treatment and hot rolling, when making a predetermined plate thickness by cold rolling and intermediate annealing or final annealing, annealing is performed at 380 to 450
A method for producing a pale gray colored aluminum alloy plate, characterized in that the temperature is ℃.