JP3073883B2 - Aluminum alloy for die casting and member for differential - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy used for manufacturing a die-cast product and a differential member made of the aluminum alloy.

[0002]

2. Description of the Related Art A differential of an automobile is used to automatically make a difference between the rotational speeds of left and right drive wheels when the automobile passes a curve, for example, to ensure good maneuverability. It is provided in. This differential has a differential gear composed of a pinion gear and a side gear meshing with the pinion gear, and a carrier and a housing containing these. The differential carrier 1 and the housing 2 (hereinafter simply referred to as a differential carrier, a differential housing) have, for example, a shape as shown in FIG. 1 and are manufactured by ductile cast iron by gravity casting. However, in recent years, due to a demand for reduction in the weight of a vehicle, a differential carrier and a housing formed of an Al-Si-Cu-based alloy by a die-casting method have been used in a small vehicle having a displacement of 1500 cc or less.

[0003]

Although there are various types of Al-Si-Cu alloys, from the viewpoint of mechanical strength and cost, 2.0 to 4.0% of Cu, .
Aluminum alloy containing 0 to 10.0% (JISAC4
B material) is used. Also, when casting is performed by die casting using this aluminum alloy, the molten metal is injected into the mold cavity at a high speed by moving the plunger tip provided in the sleeve at about 1-2 m / sec. Shrinkage cavities are likely to occur in the cast product, and the phenomenon that the cast product is seized in the mold is likely to occur. Therefore, when the above JISAC4B material is used, measures are taken by minimizing the content of Mg (0.5% or less in the JIS standard). The above Al-Si-C
In the case of u-based alloys, there is almost no problem of shrinkage cavities and seizures, but there is a problem that mechanical strength is insufficient in applications such as differential carriers and housings.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide an aluminum alloy for die casting used for a differential member capable of obtaining a cast product having high mechanical strength without casting defects. It is to provide. Another object of the present invention is to provide a differential member made of an aluminum alloy, which is sound and has high mechanical strength.

[0005] In order to achieve the above object, a first invention is to provide
Si 10 to 12% by mass, Cu 3.7 to 4.0% by mass, M
g 0.4-0.5% by mass, the balance being substantially Al
An aluminum alloy for die casting used for a differential member comprising: a composition having a total of Cu and Mg in a range of 4.1 to 4.4 mass%.
The technical means that was adopted. In order to achieve the above object, the second invention employs a technical means in which a member for differential comprising a carrier and a housing constituting the differential is formed by die casting from an aluminum alloy having the above composition. did.

As described above, the aluminum alloy of the present invention has a Si content of 10 to 12% and a Cu content of 3.7 to 4.
0%, Mg 0.4-0.5%, and the balance substantially consists of Al, and the total of Cu and Mg is 4.1-4.
It has a composition in the range of 4%, and the reasons for limiting the components are as follows. Si is added in order to improve the flowability of the molten metal and improve the shrinkage. If less than 10%, the effect is small, and the tensile strength (σ _B ) and the proof stress (σ _0.2 ) decrease, and 12% If it exceeds, the elongation is greatly reduced. Cu is added in order to improve seizure, but if its content is less than 3.7%, its effect is small, and if it exceeds 4.0%, elongation is greatly reduced. In addition, Cu is 3.7-
When it is in the range of 4.0%, it can contribute to improvement in tensile strength and proof stress. In the case of ordinary die-casting aluminum alloys, Mg is said to act as an impurity, so that a smaller amount is better, but in the present invention, by adding this positively, it is possible to improve the tensile strength and proof stress. . However, if the content of Mg is less than 0.4%, the effect is small, and if it exceeds 0.5%, the elongation is greatly reduced. Therefore, the content of Mg is set to 0.4 to 0.5%. From the point of strength, the total content of Cu and Mg is also important. That is, when the total content of Cu and Mg is less than 4.1%, the tensile strength and the proof stress decrease, and when the total content of Cu and Mg is more than 4.4%, the elongation decreases. And the total content of Mg is in the range of 4.1 to 4.4%.
The amount of impurities contained in the aluminum alloy of the present invention is preferably as small as possible in order to prevent a decrease in mechanical strength.
For example, Zn and Fe are 1.0% or less and Mn is 0.50%
Hereinafter, it is desirable that Pb is 0.20% or less and Sn is 0.10% or less.

The cast product obtained by die casting with the aluminum alloy of the present invention can be used as it is, and if necessary (to obtain a higher mechanical strength), a heat treatment (T6 treatment) can be performed. May be applied. The heat treatment conditions include, for example, a solution treatment at a temperature of 510 to 540 ° C. for 2 to 4 hours, water quenching, and a temperature of 140 ° C. for 2 hours.
The aging treatment may be performed for up to 6 hours. When heat treatment is performed, it is effective to add a small amount of Sr to the aluminum alloy in order to refine the crystal structure. However, if the added amount of Sr is small, the effect is not obtained, and if the added amount is large, segregation is liable to occur. Therefore, the range of 100 to 200 ppm is preferable.

[0008]

The aluminum alloy of the present invention has a mass percentage of Si
And Cu and Mg,
3.7-4.0%, Mg 0.4-0.5% and Cu
And Mg only contain a specific amount such as 4.1 to 4.4%, so that good molten metal flowability can be secured during die casting, shrinkage cavities can be extremely reduced, and mechanical strength ( A cast product with high tensile strength, proof stress, and elongation can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below. A molten metal of an aluminum alloy having 11 kinds of compositions shown in Table 1 (temperature: 680 to 700 ° C.) was prepared, and a differential carrier shown in FIG. 1 was cast using a rigid die-casting machine. Here, each molten metal (temperature 680 to 700 ° C.) is moved into a mold (temperature 1) by moving a plunger tip at 2 m / sec.
(50 ° C.) and then solidified. The main dimensions of the differential carrier are D ₁ = 200 mm, D
₂ (outer diameter) = 50 mm, D ₃ (inner diameter) = 40 mm, h = 3
00 mm. A sample was cut out from the flange portion of each differential carrier, and the mechanical strength was measured. The results are also shown in Table 1.

[0010]

[Table 1]

From Table 1, it can be seen that according to the alloys of the present invention shown in Examples 1 to 6, at least one of tensile strength, proof stress and elongation is improved as compared with those of Comparative Examples shown in Examples 7 to 11. Recognize. In addition, according to the alloy of Example 7, seizure was large.

[0012]

As described above, the aluminum alloy of the present invention has a high content of Si and contains only specific amounts of Cu and Mg, which were conventionally considered to be preferably low. If a differential member is formed by die casting, a cast product having high mechanical strength can be obtained. Further, since the differential carrier and the housing having the alloy composition of the present invention have high mechanical strength, they can be used as they are without heat treatment after casting.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a differential carrier housing.

[Explanation of symbols]

 1 differential carrier, 2 differential housing

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 21/00-21/18

Claims (2)

(57) [Claims] 1. Si 10 to 12% by mass, Cu 3.7 to
4.0 mass%, containing 0.4 to 0.5 mass% of Mg, the balance being substantially composed of Al, and the sum of Cu and Mg being in the range of 4.1 to 4.4 mass%. de, characterized
Aluminum alloy for die casting used for differential materials . 2. A differential member comprising a carrier and a housing constituting a differential, the die member being formed by die casting using the aluminum alloy according to claim 1.