JPH07268530A - Aluminum alloy for high pressure casting - Google Patents

Abstract

PURPOSE:To improve the strength of an aluminum allay for high pressure casting without deteriorating its ductility. CONSTITUTION:This aluminum alloy for high pressure casting is the one contg. 6 to <12% Si, >0.7 to <1.0% Cu, 0.30 to 0.60% Mg, 0.005 to 0.1% Ti and, if desired, further contg. 0.0001 to 0.004% B. Thus, the ductility equal to that of the conventional material is secured, and furthermore, its strength is improved compared to that of the conventional material. The more thinning and lightening in weight of the product using the same alloy are made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment type high pressure casting aluminum alloy which is excellent in strength and ductility and is suitable as a drive system for automobiles, suspensions, engine parts and other mechanical parts.

[0002]

2. Description of the Related Art In recent years, the weight and thickness of parts have been reduced in order to reduce the heat cost and performance of automobiles. Is required. From such a background, in place of cast iron that has been conventionally used as a material for automobile parts, an Al alloy high-pressure cast product that can be heat-treated, has excellent mechanical properties, and is lightweight is increasingly used. And, as the material of the above-mentioned Al alloy high-pressure cast product, Al-Si having excellent mechanical properties is used.
A JIS AC4CH alloy, which is a Mg-based casting alloy, is often used.

[0003]

By the way, recently, there has been an increasing demand for weight reduction and thickness reduction of the above-mentioned automobile parts, and the mechanical properties (strength, ductility) required for the materials used are more severe. It has become. However, AC4C, which has been conventionally used as a material for automobile parts,
Although the H alloy has good ductility, it has a tensile strength of 30.
It is about kg / mm ² , and the strength is insufficient to make the parts thinner and lighter. On the other hand, it is conceivable to use other known Al alloys having higher strength instead of the AC4CH alloy, but it is difficult to use these materials as materials for automobile parts and the like because of insufficient ductility. Is.

From the above viewpoints, the present inventors have conducted extensive research to develop a high-pressure casting alloy having high strength and excellent elongation. As a result, a small amount of Al-hypoeutectic Si alloy has been obtained. It has been found that the strength can be improved without lowering the elongation by containing an appropriate amount of Cu and Mg. The present invention has been made on the basis of such findings, and provides an aluminum alloy for high pressure casting which has higher strength than the AC4CH alloy and has an elongation equal to or higher than that of the AC4CH alloy. To aim.

[0005]

That is, the aluminum alloy for high pressure casting according to the present invention has a Si content of 6 to 12% by weight.
%, Cu: more than 0.7 to less than 1.0%, Mg: 0.3
It is characterized by containing 0 to 0.60%, Ti: 0.005 to 0.1%, and the balance being Al and unavoidable impurities. The aluminum alloy for high pressure casting according to the second aspect of the present invention, in addition to the above components, has a weight ratio of B: 0.0001 to
It is characterized by containing 0.004%. The Al alloy of the present invention is suitable as a material for automobile parts, but the application of the present invention is not limited to this, and may be used as a material for various machine parts other than automobile parts. It is possible. Further, the alloy of the present invention is usually subjected to solution treatment, quenching, and heat treatment such as aging after melting.

[0006]

According to the present invention, high strength can be obtained as compared with the conventional material, and elongation equal to or higher than that of the conventional material can be secured, and a material having high strength and high ductility can be obtained. Next, the reasons for limiting the component composition of the Al alloy for high pressure casting of the present invention will be described. (A) Si: less than 6 to 12% Si is contained in order to improve castability such as melt flowability, shrinkability, and casting crack prevention, and further improve strength.
However, if the content is less than 6%, these effects are not sufficient. On the other hand, if the content is 12% or more, huge primary crystal Si particles are generated and the ductility is remarkably reduced. The amount was set to 6 to less than 12%. For the same reason, it is desirable to limit the content to 6 to 10%.

(B) Cu: more than 0.7 to less than 1.0% Cu is contained in order to improve strength by aging without lowering ductility. However, if it is 0.7% or less, the effect of improving the strength is small and the ductility is also poor. This is because when Cu is added in a small amount, the elongation decreases, and 0.3 to 0.5
This is because the ductility equal to or higher than that of the Cu-free additive can be obtained by increasing the content after taking the lowest value at about%, and adding more than 0.7%. On the other hand, when the content is 1.0% or more, the strength improving effect is saturated and the castability and corrosion resistance are significantly deteriorated. Therefore, the Cu content is more than 0.7% to 1.0.
Defined to be less than%. For the same reason, it is desirable to limit the content to 0.8 to 0.9%. (C) Mg: 0.30 to 0.60% Mg is contained in order to combine with Si and precipitate as a fine Mg ₂ Si compound to improve the strength. However,
If it is less than 0.30%, the effect cannot be obtained and desired high strength cannot be secured. On the other hand, even if the content exceeds 0.6% 0, the increase in strength is saturated and the ductility is significantly reduced, so the Mg content is 0.30 to 0.6.
It was set to 0%. For the same reason, 0.35-0.55%
It is desirable to limit to.

(D) Ti: 0.005 to 0.1% Ti is added to refine the cast structure and prevent casting cracks. However, if it is less than 0.005%, the desired effect cannot be obtained, while if it exceeds 0.1%, a coarse intermetallic compound is generated and the ductility decreases, so the Ti content is 0.005%. ˜0.1%. For the same reason, it is desirable to limit the content to 0.01 to 0.08%. Further, the coexistence of 0.0001 to 0.004% of B has a function of promoting the above effect of Ti, so that it may be added together with Ti if desired. Since Fe in the unavoidable impurities causes a decrease in ductility, it is desirable to suppress it to 0.2% or less.

[0009]

EXAMPLE An example of the present invention will be described below. Table 1
The Al alloy melt of the component shown in is melted by a normal melting method,
It was injected into a mold at a pressure of 1000 kg / cm ² and high pressure casting was performed. 20 mm diameter and 200 mm length obtained as a result
A JIS No. 4 test piece was cut out from the ingot and heat treated at T6 (solution temperature 525 ° C, water cooling, aging 160 ° C, 8hr)
After performing, the tensile test was performed. The results are shown in Table 2.

[0010]

[Table 1]

[0011]

[Table 2]

As is clear from Table 2, the alloy of the present invention has a tensile strength of about 40 kg / mm ² or more and an elongation of 9% or more, and exhibits excellent properties in both strength and elongation. On the other hand, in the comparative alloys, those with high elongation have low strength, and those with high elongation have low elongation,
The balance between strength and elongation is poor, making practical application difficult. In addition, No. with a high Cu content. The comparative alloy of No. 10 was good in both strength and elongation, but was poor in castability and caused casting cracks.

[0013]

As described above, the aluminum alloy for high pressure casting of the present invention has a weight percentage of Si: 6 to less than 12%, Cu: more than 0.7 to less than 1.0%, Mg: 0.30. ~
Since it contains 0.60%, Ti: 0.005 to 0.1%, and optionally B: 0.0001 to 0.004%, the strength can be improved without lowering the elongation. For example, by using it as a material for automobile parts, it becomes possible to reduce the thickness and weight of automobile parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Okazaki 5-3-8, Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Yoichi Taniguchi 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Co., Ltd. (72) Inventor Kenji Kato 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Co., Ltd. (72) Inventor Yoshimitsu Fukui 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Industry Co., Ltd.

Claims (2)

[Claims] 1. Si: 6 to less than 12% by weight, Cu:
Greater than 0.7 to less than 1.0%, Mg: 0.30 to 0.60
%, Ti: 0.005 to 0.1%, with the balance being Al
Aluminum alloy for high pressure casting consisting of unavoidable impurities 2. In addition to the components of claim 1, further% by weight
B: 0.0001 to 0.004% is contained in the aluminum alloy for high pressure casting.