JPH0598379A - Aluminum alloy for casting and engine air intake parts for automobile use - Google Patents

Abstract

PURPOSE:To obtain an aluminum alloy for casting, where the inside and the outside do not communicate with each other in the thick-walled part and the thin-walled part in the vicinity of the above, and also to obtain engine air intake parts for automobile use. CONSTITUTION:The alloy has a composition consisting of, by weight ratio, 4.0-10.0% Si, <=4.5% Cu, <=0.5% Mg, and the balance Al with inevitable impurities. Moreover, the micro shrinkage cavities where the correlation between the aspect ratio of the shrinkage cavity shape and the area ratio lies in the prescribed range are formed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to Al-S having excellent castability.
Based on i-system, Mg to improve mechanical properties
The present invention relates to a casting aluminum alloy in which shrinkage cavities are finely dispersed in an aluminum casting alloy to which is added.

[0002]

2. Description of the Related Art When an aluminum alloy is cast, there are cases in which a dent is formed due to shrinkage in a thick-walled portion or the like where the wall thickness changes greatly. When such a cast product is a product that causes a pressure difference between the inside and the outside such as a manifold of an engine intake component for automobiles, and if a dent is generated in the boss portion where the screw is processed, the dent is exposed on the inner surface of the screw after the screw is processed. , The inside and outside may be connected by a very small passage, and the intake performance may deteriorate, resulting in a defective product.

Conventionally, various measures have been taken in order to prevent the formation of these scratches, for example, Japanese Patent Laid-Open No. 1-756.
No. 43 publication, Si: 10 to 13%, Sr: 0.01
~ 0.06%, Sb: 0.01-0.06% Al-S
If necessary, Bi is added to the i-based alloy, or Si: 8 to
13%, Mg: 0.5 to 1.5%, Cu: ≤ 0.45
%, Ti: ≤ 0.2%, Mn: ≤ 0.5%, Ni: 0.
5 to 1.5%, Sr: 0.01 to 0.06%, Sb:
There is a disclosure of an example in which Bi is added as necessary to an Al-Si-Mg-based alloy of 0.01 to 0.06% to disperse a gas in a molten aluminum alloy. In addition, JP-A-1-7564
Japanese Patent Publication No. 4 discloses that by containing Bi: 0.01 to 0.2%, shrinkage cavities are reduced and a sound casting is obtained.

[0004]

In the aluminum cast product, even if the above-mentioned dents and shrinkage cavities are reduced, the inside and outside of the cast product may be connected to each other, and the performance as an automobile engine intake part may not be exhibited. .. That is, even when the micro-shrinkage is dispersed and generated by eliminating the Zaku nest, if the area ratio of the shrinkage itself is high, or conversely even if the area ratio is low, the flattening of the shape of the shrinkage is remarkable. , Individual micro-shrinkages may be easily connected and a leak path may be formed between the inside and outside of the cast product. Especially in thin-walled parts near the thick-walled part, micro-shrinkage often occurs due to the effect of the thick-walled part. In addition, since the distance between the inside and the outside of the cast product is short, the inside and the outside are connected to each other, so that the intake performance cannot be obtained, and these are defective casting products.

An object of the present invention is to provide an aluminum alloy for casting and an automobile engine air intake component in which the inside and outside are not connected to each other at the thick portion and the thin portion in the vicinity thereof.

[0006]

Means for Solving the Problems The present inventor has paid attention to the form of a microshrinkage and has decided to control this form. In the thin-walled portion of the aluminum alloy for casting including the thick-walled portion, the inside and outside are connected. We have found that it can be eliminated.

That is, the casting aluminum alloy of the present invention is
By weight ratio, Si: 4.0 to 10.0%, Cu: 4.5%
Hereinafter, it is characterized in that Mg: 0.5% or less, the balance Al, and unavoidable impurities are generated, and the microshrinkage in which the correlation between the aspect ratio of the microshrinkage shape and the area ratio is within a certain range is generated. Here, the aspect ratio is the ratio of the major axis and the minor axis of the microshrinkage,
The area ratio is the incidence of microshrinkage.

Next, the automobile engine intake component of the present invention comprises the composition of the aluminum alloy for casting.

[0009]

[Function] In order to solidify the entire casting at the same time to disperse and refine the gas porosity and microshrinkage,
And Cu content is regulated.

Si is used in order to improve the flowability of molten metal.
0 to 10.0%, preferably 6.5 to 7.0% is contained.

Cu is contained in an amount of 4.5% or less, preferably 3.2 to 3.4% in order to improve the mechanical strength.

By generating a microshrinkage in which the correlation between the aspect ratio of the microshrinkage shape and the area ratio is within a certain range, depending on the cast product, the microshrinkage is not connected to the inside or the outside of the cast product and is airtight. No leakage occurs.

[0013]

Next, the present invention will be described in detail with reference to an embodiment. FIG. 2 is a casting plan modeled on a manifold, which is an engine air intake component for automobiles, showing an embodiment of the present invention, in which a thin portion 2 having a thickness of 2.5 mm, a boss of a thick portion 1 having a diameter of 15 mm and both ends are provided. It has a flange 3 with a wall thickness of 12 mm.
Using this manifold model as the casting target, casting was performed in lots with different chemical compositions.

The airtightness of the cast manifold model was examined by an airtightness tester (atmospheric pressure 3 Kg / cm 2).
The leak results for each casting component are shown in Table 1, and the cumulative number of leak points is shown in FIG.

[0015]

[Table 1] Number of lots inspected Si Cu Sr H2 gas amount No. (pieces) (%) (%) (%) CC / 100g Airtight and leaky nest 1 5 7.3 2.8 400 0.3 or more (5 pieces) None to 7.6 ~ 3.0 ~ 500 25 7.0 2.8 400 0.3 or more Yes (4 pieces) None ~ 7.3 ~ 3.0 ~ 500 3 5 6.5 3.2 400 0.3 or more None None ~ 7.0 ~ 3.3 ~ 500

Further, the thick portion 1 of the cast manifold described above.
The cross section of the boss is shown in FIG. In FIG. 3A, the aspect ratio of the microshrinkage was 1.98, the area ratio of the microshrinkage was 4.5%, and airtightness leaked.

In FIG. 3 (B), the aspect ratio of the microshrinkage was 1.78 and the area ratio of the microshrinkage was 1.8, but airtightness did not occur.

In FIG. 3C, the aspect ratio of the microshrinkage was 1.33 and the area ratio of the microshrinkage was 7.8%, but no airtightness occurred.

FIG. 1 is a diagram showing the relationship between the aspect ratio, the area ratio, and the airtightness of the micro-shrinkage generation form. From Table 1 and FIG. 4, the boss 1 is the place where leakage occurs.
And a thin portion of the pipe near the thick portion of the flange 3, S
It can be seen that the leakage may occur depending on the difference in the i and Cu contents. Further, it can be seen from FIG. 1 that the occurrence of leakage is seen from the relationship between the aspect ratio and the area ratio of the microshrinkage. That is, even if the shape of the microshrinkage is distorted and the aspect ratio is low as shown in FIG. Even if the leakage path is not connected between them and the microshrinkage area ratio is high as shown in FIG. 3C, the shape of the microshrinkage is round and the aspect ratio is high. As described above, it is possible to prevent leakage of the aluminum alloy for casting and the engine intake parts for automobiles by controlling the generation mode of micro-shrinkage and the casting composition.

[0020]

As described above, in the cast aluminum alloy containing Si, Cu, Mg, the balance Al and unavoidable impurities, by controlling the aspect ratio and area ratio of the micro-shrinkage generation form within a certain range, Prevents leakage due to micro-shrinkage in the thin part near the
It is very effective when used for automobile engine intake parts such as manifolds that require airtightness.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an aspect ratio, an area ratio, and an airtightness in a micro-shrinkage form according to an embodiment of the present invention.

FIG. 2 is a diagram showing a casting method using a manifold as a model showing an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between microshrinkage morphology and leakage in the model shown in FIG.

FIG. 4 is a diagram showing a cumulative total of locations where leakage occurs in the model shown in FIG.

[Explanation of symbols]

 1 Thick part 2 Thin part 3 Flange 4 Pushing water 5 Runway

Claims (2)

[Claims] 1. A weight ratio of Si: 4.0 to 10.0%,
Cu: 4.5% or less, Mg: 0.5% or less, the balance Al and unavoidable impurities are contained, and the microshrinkage in which the correlation between the aspect ratio of the microshrinkage shape and the area ratio is within a certain range is generated. Aluminum alloy for casting characterized by. 2. A weight ratio of Si: 4.0 to 10.0%,
Cu: 4.5% or less, Mg: 0.5% or less, a balance of Al and unavoidable impurities, and casting to generate a microshrinkage in which the correlation between the aspect ratio and the area ratio of the microshrinkage is within a certain range. Automotive engine intake parts characterized by being cast using an aluminum alloy for automobiles.