JPS5810456B2 - Aluminum alloy for die casting - Google Patents

Description

[Detailed description of the invention] The present invention relates to an aluminum alloy for die casting.

More specifically, the present invention relates to a die-casting alloy that contains manganese and vanadium alloying elements, has good die-casting properties, is strong, and provides a beautiful silvery to reddish, glossy, and uniform anodic oxide film.

Recently, there has been a strong desire to develop an aluminum alloy for die casting that has excellent surface treatment properties, corrosion resistance, and mechanical properties, and particularly in terms of surface treatment properties, it can be treated with anodizing to give a beautiful, uniform, and glossy surface.

However, in general, there is a trial-and-error relationship between anodizing properties and die-casting properties or mechanical strength.

The present inventors investigated die-casting alloys that satisfy the above-mentioned characteristics, and found that aluminum alloys containing specific amounts of manganese and vanadium have superior die-castability and mechanical strength compared to ordinary commercial pure aluminum. Moreover, it was discovered that an anodic oxide film with a uniform color tone ranging from silver to reddish can be produced, and the present invention was achieved.

That is, the present invention is an aluminum alloy for die casting consisting of 1.7 to 4.0% manganese, 0.05 to 0.6% vanadium, impurities of 0.5% or less, and the balance aluminum.

Among the above components, manganese is responsible for die casting properties, surface treatment properties and mechanical properties.

When the amount of manganese is less than 1.7%, the flowability during die casting is poor and defects often occur during die casting.

Furthermore, the mold releasability, prevention of seizure, mechanical strength, and color development of the oxide film during anodic oxidation are insufficient.

Furthermore, if the amount of manganese exceeds 4.0%, the melting temperature of the alloy will increase, making die casting at high temperatures necessary.
This is disadvantageous in practice.

Furthermore, the elongation is significantly reduced, and the formation of the anodic oxide film becomes uneven.

Therefore, the manganese content needs to be 1.7 to 4.0%.

The preferred content of manganese is 1.8-2.5%.

Vanadium has the effect of making the naturally colored tone of the anodic oxide film even more brilliant due to the addition of manganese, and giving the impression that the gloss has further increased.

It also has the effect of improving the mechanical strength of the alloy, the mold scorching property, and the mold releasability.

If the amount of vanadium is less than 0.05%, there is no effect, and if it is too much, the melting temperature increases and the color tone of the oxide film deteriorates due to the formation of crystallized substances, both of which are undesirable.

Therefore, the content of vanadium needs to be 0.05 to 0.6%.

The preferred content of vanadium is 0.15-0.4%.

Also, in the alloy, iron is an inevitable impurity of aluminum.
Contains silicon etc.

Iron is generally an alloying element added to improve the mold releasability of aluminum alloys for die casting, but in the present invention, iron is added by 0.3 to prevent unevenness and graying of the anodic oxide film.
% or less.

If silicon increases, the anodic oxide film becomes uneven, so 0.
It is desirable that the content be 2% or less, particularly 0.1% or less.

The total amount of impurities including these is 0.5% or less.

Die-cast products using the alloy of the present invention are subjected to blasting treatment,
After undergoing mechanical processing such as cutting, or in the case of die-cast products whose surface has been roughened using a die-cast mold that has been given fine irregularities in advance, the product may be left as is and subjected to chemical polishing or electrolytic polishing. Thereafter, a uniform silver to reddish anodic oxide film can be formed on the surface of the die-cast product by carrying out anodization treatment using a normal sulfuric acid method.

Furthermore, die-cast products using the alloy of the present invention can be uniformly colored by dyeing.

As described above in detail, according to the present invention, it is possible to provide an aluminum alloy for die casting that is excellent in die casting properties, mechanical strength, uniformity of anodized film, and brightness.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Manganese 2.0%, vanadium 0.31%, iron 0.16
%, silicon 0.08%, and the balance aluminum, using a horizontal cold chamber type die casting machine (manufactured by Toshiba Machine Co., Ltd., DA250B type), at a mold temperature of 200%.
C1 casting pressure 860 kg/cri, sprue speed 25 m/sec, casting temperature 750°C, upper surface outer diameter 60.0 mm, inner diameter 52.8 mm, lower surface outer diameter 55.8 mm, inner diameter 47.8
When a cylindrical casting with a thickness of 4711 mm and a height of 60 mm was die-cast, there was no shrinkage on the surface of the casting, and it showed good die-casting properties with no welding to the mold.

The outer surface of the obtained cylindrical casting was cut by 0.2rm, degreased with a solvent (ligroin), and then heated at 95 to 100°C.
A chemical polishing treatment was performed by immersing it in a mixed aqueous solution of phosphoric acid and nitric acid for 40 seconds.

After washing this material with water, it was placed in a 15% sulfuric acid aqueous solution at a night temperature of 2.
When anodizing was performed for 6 minutes at 0° C. and a current density of 1.5 A/di2, a silvery white, glossy, uniform film with no visible hot water flow pattern or hot water wrinkles was obtained on the cut surface of the casting.

When anodic oxidation was performed for 30 minutes, a uniform film with a reddish-brown luster and no visible hot water flow pattern or hot water wrinkles was obtained.

The Brinell hardness of this casting was HE40.

Example 2 Manganese 2.3%, vanadium 0.29%, iron 0.16
When an alloy consisting of 0.08% silicon and the balance aluminum was die-cast under the same conditions as in Example 1, it showed good die-casting properties with no shrinkage on the casting surface and no welding to the mold.

The obtained cylindrical casting was cut, degreased, and
A chemical polishing treatment and water washing were performed, and then an anodizing treatment was performed for 6 minutes under the same conditions as in Example 1.

As a result, a silver-white, glossy, uniform film with no visible melt flow patterns or creases was obtained on the cut surface of the casting.

When anodic oxidation was performed for 30 minutes, a reddish-brown, glossy, uniform film with no visible hot water pattern or hot water wrinkles was obtained.

The Brinell hardness of this casting was HE11.

Example 3 Manganese 2.0%, vanadium 0.15%, iron 0.15
%, silicon 0.08%, and the balance aluminum was die-cast under the same conditions as in Example 1, and showed good die-casting properties with no shrinkage on the casting surface and no welding to the mold.

The obtained cylindrical casting was cut, degreased, and
A chemical polishing treatment and water washing were performed, and then an anodizing treatment was performed for 6 minutes under the same conditions as in Example 1.

As a result, a silvery-white, glossy, uniform film with no visible molten metal flow pattern or molten metal wrinkles was obtained on the cut surface of the casting.

When anodic oxidation was carried out for 30 minutes, a reddish-brown, glossy, uniform film with no visible hot metal flow pattern was obtained.

The Brinell hardness of this casting was HE11.

Example 4 Manganese 2.0%, vanadium 0231%, iron 0.16
%, silicon 0.08%, and the balance aluminum, using a horizontal cold chamber type die casting machine (DA250B type manufactured by Toshiba Machine Co., Ltd.) at a mold temperature of 250°C.
When a flat plate of 150 x 75 x 3 mm was die-cast at a casting pressure of 860 kg/ffl, a casting temperature of 750°C, and a sprue speed of 15 m/sec, there was no shrinkage on the casting surface, and,
It showed good die-casting properties with no welding to the mold.

The surface of the obtained flat plate casting was roughened by shot blasting, then degreased, chemically polished and washed with water under the same conditions as in Example 1, and then anodized under the same conditions as in Example 1 for 6 minutes.

As a result, a silvery-white, glossy, uniform film with no visible melt flow patterns or creases on the casting surface was obtained.

When anodic oxidation was performed for 30 minutes, a reddish-brown, glossy, uniform film with no visible hot water pattern or hot water wrinkles was obtained.

Comparative example 1 Manganese 0.78%, vanadium 0.27%, iron 0.1
When an alloy consisting of 2% silicon, 0.05% silicon, and the balance aluminum was die-cast under the same conditions as in Example 4, there was no welding to the mold, but shrinkage was present on the entire surface of the casting.

Comparative example 2 Manganese 0.81%, Vanadium 0.30%, Iron 0.1
When an alloy consisting of 6% silicon and 0.07% aluminum was die-cast under the same conditions as in Example 1, there was no welding to the mold, but a small amount of welding was present on the inner surface of the casting.

Claims (1)

[Claims] 1. Manganese 1.7-4.0%, vanadium 0.05-4.0%
An aluminum alloy for die casting consisting of impurities of 0.6%, 0.5% or less, and the balance aluminum. 2. An aluminum alloy for die casting according to claim 1, wherein the manganese content is 1.8 to 2.5% and the vanadium content is 0.15 to 0.4%.