JPH0256417B2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention]

(Field of Industrial Application) The present invention relates to a milky-white colored aluminum alloy that is used to develop a milky white color through anodizing treatment, and more specifically, the present invention relates to a milky-white colored aluminum alloy that is used to develop a milky white color through anodizing treatment, and more specifically, it is possible to obtain an opaque anodic oxide film appearance with strong whiteness. The present invention also relates to a milky-white colored aluminum alloy which has good extrudability and corrosion resistance and weather resistance equivalent to that of the 6063 alloy, and which can also be subjected to artificial aging treatment after extrusion to obtain mechanical properties equivalent to those of the 6063 alloy. (Prior art) Aluminum alloy building materials such as sash wood are required to have a variety of colors, and in addition to various colors such as gold, bronze, and black,
There is also a strong demand for opaque light color tones, which are described as "milky white" or "pastel tone." As a method for surface-treating and coloring aluminum alloys, a method has recently been widely used in which a naturally colored alloy is used and each color tone is obtained by anodizing. For example, as an aluminum alloy from which a film with a milky white color can be obtained by anodizing treatment, an aluminum alloy to which Mn and Co are added is disclosed in JP-A-50-16631. (Problems to be Solved by the Invention) However, the color tone obtained with naturally colored alloys is determined by the alloy components, so the desired color tone and
It is generally difficult to design alloy components, such as adjusting the balance between the strength and other properties of the alloy. In other words, the aluminum alloy described in JP-A-50-16631 is a die-casting alloy, and even though it develops a milky white color through anodizing, the present invention is not good in terms of malleability and age hardenability. There was a problem in that the performance as a structural material for construction such as the target sash frame could not be ensured. (Object of the Invention) The present invention has been made to solve the above-mentioned problems of conventional milky-white colored aluminum alloys.
The objective is to obtain a highly white, opaque, milky-white film appearance through anodizing treatment, and to achieve the same extrudability, strength, and strength as 6063 alloy.
The purpose of the present invention is to provide an age-hardening aluminum alloy with corrosion resistance and weather resistance.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the inventor of the present invention has conducted extensive studies on the influence of alloy components on the color tone, extrudability, age hardenability, etc. of the color produced by anodizing treatment, and as a result, Al-Mg can obtain mechanical properties suitable for architectural structural materials through artificial aging treatment after extrusion
- By adding Fe to the Si-based alloy in a range that does not affect the strength after aging treatment, the appearance color tone of the film after anodizing treatment in a regular sulfuric acid bath can be made opaque. Furthermore, by adding Co, a highly white film appearance color tone can be obtained.
It was discovered that the effects of both Fe and Co can produce a "milky white" external color tone of the anodic oxide film. The milky white aluminum alloy according to the present invention is based on the above knowledge, and has a Fe content of 0.30% by weight.
~0.7%, Co: 0.05~1.0%, Mg: 0.30~0.7%,
It is characterized by containing 0.20 to 0.6% Si, with the remainder consisting of Al and inevitable impurities. Below, the reasons for limiting the component values (wt%) of the milky-white colored aluminum alloy according to the present invention will be described. Fe: 0.30-0.7% Fe is an element necessary to obtain an opaque anodic oxide film appearance color tone when an extruded shape is anodized in a sulfuric acid bath, but if it is less than 0.30%, it will have no effect. is not obtained. Conversely, if it exceeds 0.7%,
Fe crystallizes Al-Fe-Si intermetallic compounds during casting, and when artificial aging treatment is performed after extrusion processing,
It reduces the amount of Mg ₂ Si or free Si that is effective for hardening, making it impossible to obtain the same strength as 6063 alloy. Therefore, Fe is limited to a range of 0.30 to 0.7%. Co: 0.05-1.0% Co is an element necessary to obtain a film with strong whiteness by anodizing the extruded shape in a sulfuric acid bath. The combination of these two effects creates a pastel milky white color tone. However, if it is less than 0.05%, it has no effect, and if it exceeds 1.0%, the effect is saturated and there is no further effect. In addition, Co, together with the aforementioned Fe, has the effect of accelerating the dissolution reaction during the matting process with caustic soda as a pretreatment process for anodizing treatment, making it easier to eliminate the dice marks that occur on the fabric surface during the extrusion process. Not only that, the film produced by the subsequent anodizing treatment has a low gloss color tone, which, together with the aforementioned opacity and whiteness, has the effect of providing a damp and calm appearance. Furthermore, Co has a significantly less adverse effect on strength after aging treatment than Fe, and the amount of Co added is not limited in terms of mechanical properties. Furthermore, there is virtually no effect on extrudability within this range. Mg: 0.30~0.7% Mg is a hardening element through artificial aging treatment
It is an element necessary to form Mg ₂ Si, and Mg
If it is less than 0.30%, the specified strength cannot be obtained;
If it exceeds 0.7%, the extrudability of the alloy will deteriorate. Note that the effect of Mg on the appearance color tone of the film after anodizing treatment is relatively small. Si: 0.20-0.6% Si, along with the aforementioned Mg, forms Mg ₂ Si, which is a hardening element through artificial aging treatment, and also forms excess free Si.
It is an element necessary to obtain strength, and Si is
If it is less than 0.20%, it will not be possible to obtain the same strength as 6063 alloy, and if it is more than 0.6%, natural coloring due to Si will occur during anodizing treatment, resulting in a grayish and dull appearance, which is undesirable. Next, in order to homogenize the structure of the aluminum alloy of the present invention, it is necessary to perform homogenization heat treatment after casting into a billet shape and before extrusion processing. The heat treatment temperature is preferably 550 to 600℃ in order to promote the change of Al-Fe intermetallic compounds to Al ₃ Fe and make it milky white, but if productivity is not considered, it will take a long time even below 550℃. This is possible by processing time. In addition, when surface-treating the extruded shape of the aluminum alloy according to the present invention, degreasing, etching, and smut removal are performed according to conventional methods, and anodizing treatment is performed using a commonly used method such as a sulfuric acid bath. There are no particular limitations on the processing conditions. (Example) Molten aluminum alloys A to C having the respective compositions shown in Table 1 were cast at a semi-continuous casting method.
Cast into a billet shape with a diameter of 155 mm at 100 m/min,
After homogenization heat treatment at 590°C for 10 hours, it was extruded into a hollow shape (〓 shape) used for building materials. Next, artificial aging treatment was performed at 190℃ for 2.5 hours, and anodization treatment was performed for 32 minutes at a current density of 1.5A/ ^dm2 in an electrolytic bath with a sulfuric acid concentration of 130g/dm to form an anodic oxide film with a thickness of 15μm. I let it happen.

[Table] (Comparative example) As comparative alloys, the molten metals of aluminum alloys D and E shown in Table 1 were mixed with the above-mentioned invention alloy A.
- Casting, homogenization heat treatment in the same manner as in case of C,
Extruded. Next, similarly artificial aging treatment,
Anodizing treatment (thickness: 15 μm) was performed. (Evaluation) The color tone and gloss of the anodic oxide film of the shapes made of the alloys A to C of the present invention and comparative alloys D and E obtained by the above procedure were measured. In addition, its corrosion resistance
The mechanical properties of each profile were also measured as well as evaluated by a 16 hour cast test. The color tone of the oxide film was measured using a colorimeter (0-45° method) manufactured by Suga Test Instruments, and expressed as the L ^* value specified in JIS Z8729. This L ^* value represents brightness, and the higher the L ^* value, the whiter it is. These results are shown in Table 2, and the alloys A to A of the present invention having components within the range specified in the present invention
With C, it was confirmed that a bright milky white color with low glossiness was developed, and this tendency became more pronounced as the Co content increased, resulting in a calm milky white color. On the other hand, Comparative Alloys D and E developed a dull color with no brightness, and this tendency was particularly noticeable in the conventional 6063 alloy, resulting in a film tone with low brightness and high surface gloss. Regarding corrosion resistance, as a result of a 16-hour cast test, both the invention alloy and the comparative alloy showed a good value of RN (Rating Number) of 9.8. Regarding mechanical properties, alloys A to C of the present invention had slightly lower strength than comparative alloys D and E, but it was confirmed that they fully satisfied the specifications for 6063 alloy T5 treated materials. Furthermore, as for the extrudability, since the amount of added alloy was small, the extrudability was on the same level as 6063 alloy, and there was no problem in extrusion processing. As a result of the above evaluation tests, the present invention alloys A to C are as follows:
Not only do they have a bright, calm milky white color, but they are also comparable to conventional alloys in terms of corrosion resistance and mechanical properties, and it has been confirmed that they can withstand the same use as 6063 alloy as extruded materials for building materials. Ta.

【table】

【Effect of the invention】

As explained above, the milky white colored aluminum alloy according to the present invention is an Al-Mg-Si alloy containing Fe.
By simultaneously adding Co, the effects of opacity due to Fe and whiteness due to Co are exhibited, and by anodizing, a pastel milky white color is developed. In addition, it has performance comparable to conventional 6063 alloy in terms of corrosion resistance, mechanical properties, and extrudability, and is expected to have a wide range of uses as an aluminum alloy, mainly for building materials that require a variety of colors. .

Claims (1)

[Claims] 1% by weight, Fe: 0.30-0.7%, Co: 0.05-1.0
%, Mg: 0.30 to 0.7%, Si: 0.20 to 0.6%, and the balance consists of Al and inevitable impurities.