JPH093582A - Aluminum alloy casting excellent in strength and toughness and method for producing the same - Google Patents

Abstract

(57) [Summary] [Structure] Mg: 3.0 to 5.5%, Zn: 1.0 to 2.0% (Mg
/Zn:1.5-5.5), Mn: 0.05-1.0%, Cu: 0.0
It contains 5 to 0.8% and Fe: 0.10 to 0.8%, consists of the balance Al and inevitable impurities, and crystallized substances are spheroidized and dispersed in the alloy matrix. It is preferable to apply and manufacture by high pressure casting. [Effect] An aluminum alloy casting having high strength and high toughness can be obtained even in the cast state without heat treatment. The aluminum alloy casting is particularly useful for automobile suspension parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy casting having excellent strength and toughness and a method for producing the same, and in particular, enables high strength and high toughness to be obtained in the as-cast state without adding heat treatment. The present invention relates to an Al-Mg-based aluminum alloy casting that can be suitably used as a steel and a method for producing the same.

[0002]

2. Description of the Related Art Aluminum alloys are often used for the purpose of reducing the weight of automobile parts. Automotive parts are required to have various characteristics depending on the location where they are used. In particular, automotive suspension parts are required to have strength and toughness. Heat-treated materials (quenched and tempered materials) and heat-treated materials of aluminum alloy castings are used.

In the manufacture of aluminum alloy forged products, cracks and defective shapes are likely to occur, especially in forged products having complicated shapes. Therefore, after the forging process, a softening process by annealing and a forging process are carried out. Must be repeated, resulting in a long process and an increase in manufacturing cost. Quenching due to heat treatment tends to cause thermal distortion, especially in products having thin-walled parts, and also causes local melting depending on the component composition, resulting in variations in dimensions and quality between products. is there.

As an aluminum alloy casting for heat treatment, for example, Mg2.5-4.5%, Si0.1-1.0%, Mn1.0
% Or less, Ti0.05 to 0.3%, B0.02% or less, Fe1.0%
Below, Be 0.001-0.1% is contained, Zn0.1-1.5
%, Cu 0.1 to 0.5%, Cd 0.05 to 0.5%, and the balance is Al and inevitable impurities. (JP-A-62-89849
This aluminum alloy casting has excellent strength and ductility, but it has a solution treatment at 560 to 600 ° C and 10
Since the tempering treatment at 0 to 300 ° C. is indispensable, the above problems cannot be solved.

[0005]

DISCLOSURE OF THE INVENTION The present invention, in order to solve the above-mentioned conventional problems in heat-treated aluminum alloy forged products and aluminum alloy castings, which are used and developed for automobile parts and the like, Especially Al-Mg
Focusing on alloy-based castings, multi-faceted experiments on the combination of contained components, the relationship between casting method and structural properties, and strength characteristics,
The purpose of the present invention is to provide an aluminum alloy casting and a method for producing the same, capable of obtaining excellent strength and toughness even in the as-cast state without heat treatment. To do.

[0006]

The aluminum alloy casting having excellent strength and toughness according to the present invention for achieving the above-mentioned object is Mg: 3.0-5.5%, Zn: 1.0-2.0% (M
g / Zn: 1.5 to 5.5), Mn: 0.05 to 1.0%, Cu: 0.0
It is characterized in that it contains 5 to 0.8% and Fe: 0.10 to 0.8%, consists of the balance Al and unavoidable impurities, and the crystallized substances in the alloy matrix are spherically dispersed.

The method for producing an aluminum alloy casting excellent in strength and toughness according to the present invention is Mg3.0-5.5.
%, Zn: 1.0 to 2.0% (Mg / Zn: 1.5 to 5.5), M
n: 0.05-1.0%, Cu0.05-0.8%, Fe: 0.10-0.
An aluminum alloy containing 8% and the balance of Al and unavoidable impurities is characterized by being subjected to high pressure casting at a pressure of 50 to 150 MPa.

Explaining the meanings of the alloy components in the present invention and the reasons for limiting them, Mg, Zn, Cu
Is a solid solution or finely precipitated in the aluminum matrix during casting to improve the strength characteristics of the alloy, and coexistence of these components is extremely important in the present invention. These elements crystallize as a relatively coarse compound during casting, but the toughness and ductility of the alloy can be reduced by making these crystallized substances not exist in a continuous state and dispersing them in the matrix by spheroidizing them. It is a feature of the present invention to improve.

The preferred content range of Mg, Zn and Cu is
Mg is 3.0 to 5.5%, Zn is 1.0 to 2.0%, and Cu is 0.05.
If the content of each of these elements is less than the lower limit, the effect of improving the strength is not sufficient, and if the content exceeds the upper limit, the amount of the crystallized substance is significantly increased even if the crystallized substance is spheroidized. It increases and impairs toughness. A more preferable content range of Mg, Zn, and Cu is 4.0 to 5.0% of Zn and 1.3 of Zn.
.About.1.7%, and Cu is 0.3 to 0.7%. In the present invention, the ratio of the Mg content and the Zn content calculated from the limit values of the Mg and Zn contents of the alloy components (Mg / Z) is also used.
n) is from 1.5 to 5.5, and in this range, the crystallized substance is likely to be spheroidized even in the as-cast state, and the decrease in toughness is suppressed.

Mn dissolves in the aluminum matrix during casting, has the function of increasing the strength of the alloy, and acts to improve the toughness by spheroidizing the needle-shaped Fe compound that inhibits the toughness of the alloy. . The preferred content is 0.
In the range of 05 to 1.0%, if less than 0.05%, strength is improved and F
e The spheroidizing effect of the compound is small. If it exceeds 1.0%, M
The toughness and ductility decrease due to the increase of the n-based compound. The more preferable content of Mn is in the range of 0.3 to 0.7%.

Fe has a function of preventing seizure of the molten aluminum alloy on the die during casting of the alloy. A preferred content range is 0.10 to 0.8%, and if it is less than 0.10%, the effect is not sufficient, and if it exceeds 0.8%, the Fe compound increases and the toughness is impaired. A more preferable Fe content range is 0.2 to 0.7%. In addition, in the present invention, in addition to the above-mentioned essential component elements, Ti of 0.1% or less, B of 0.02% or less, Be of 5 ppm or less, Ni of 1.0% or less, 0.6% or less of The characteristics can be improved by adding V or the like. Further, even if Si as an impurity is contained in the range of 1.0% or less, it does not affect the characteristics of the alloy of the present invention.

The aluminum alloy casting of the present invention can obtain the desired strength characteristics by subjecting it to ordinary die casting, followed by quenching and tempering treatment, but crystallized substances dispersed in the matrix. In order to promote the spheroidization of the steel and enhance the effect of improving the toughness and ductility, it is preferable to apply a high pressure casting method such as molten metal forging. Preferred casting temperature is 660 to 900 ° C, particularly preferred temperature is 750 to 850 ° C.
And the pressure is 50 to 150 MPa, preferably 70 to
It is in the range of 120 MPa.

[0013]

According to the present invention, the strength of the alloy matrix is determined by the coexistence of Mg, Zn and Cu, the content of Mn, and the content ratio of Mg and Zn, and the strength of the crystallized substance that is crystallized and dispersed in the alloy matrix. The properties, especially toughness, are improved, and excellent strength and toughness are achieved even in the as-cast state without heat treatment after casting. The effect of spheroidizing the crystallized product is further effectively promoted by the high pressure casting method, and an aluminum alloy casting having high strength and high toughness can be reliably obtained.

[0014]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example 1 An aluminum alloy having the composition shown in Table 1 was formed to a thickness of 25 m by a molten metal forging method (casting temperature: 800 ° C., casting pressure: 100 MPa).
After casting into a casting of m, width 25 mm, length 250 mm, JIS
A No. 4 tensile test piece and a JIS No. 3 Charpy test piece were molded and evaluated for mechanical properties and toughness.

The results are shown in Table 1. As shown in Table 1, all of the test materials No. 1 to 7 according to the present invention showed excellent strength and toughness equivalent to the 6061 forged material (T6 treated material), and A3
56 Excellent in toughness compared to cast material. When the microstructure of the test material No. 1 was observed with a microscope, it was found that the spheroidized crystallized substances were uniformly dispersed in the matrix as shown in FIG. on the other hand,
Mold casting (no-load casting) of alloy with the same composition as test material No. 1
As shown in FIG. 2, it was observed that crystallized substances were present in a continuous state in the microstructure of the casting thus obtained.

[0016]

[Table 1]

Comparative Example 1 An aluminum alloy having the composition shown in Table 2 was subjected to molten metal forging under the same conditions as in Example 1 and cast into a casting having the same dimensions as in Example 1, followed by JIS No. 4 tensile test piece and JIS No. 3 Charpy test. The pieces were molded and evaluated for mechanical properties and toughness. Table 2 shows the results. In addition, in Table 2, the values out of the conditions of the present invention are underlined.

[0018]

[Table 2]

As shown in Table 2, the test material No. 11 is
Ductility and toughness are poor because the contents of Mg and Zn exceed the upper limits. Test material No. 12 has a low strength because it contains a small amount of Mg and Zn. Since the test material No. 13 has a small Mn content, the test materials No. 14 and No. 16 have Mn contents of Mn.
Since the Cu content and the Cu content exceed the upper limits, the ductility and toughness are deteriorated, and the test material No. 15 has a low Cu content and thus a low strength. Test material No. 17 has a low Zn content (Mg / Zn:
7) Therefore, strength and toughness are poor.

[0020]

As described above, according to the present invention, it is possible to obtain an aluminum alloy casting having excellent strength and toughness, which is particularly suitable for undercarriage parts for automobiles. Since the aluminum alloy casting has excellent strength and toughness even in the cast state without heat treatment, the problems associated with forging and heat treatment are eliminated, the process is shortened, and the manufacturing cost is reduced. Can be achieved.

[Brief description of drawings]

1 is a microstructure of an aluminum alloy casting according to the present invention.

FIG. 2 is a microstructure when an aluminum alloy having the composition of the present invention is subjected to ordinary die casting.

Claims (2)

[Claims] 1. Mg: 3.0 to 5.5% (mass%, the same applies hereinafter), Zn: 1.0 to 2.0% (Mg / Zn: 1.5 to 5.5), M
n: 0.05-1.0%, Cu: 0.05-0.8%, Fe: 0.10-
An aluminum alloy casting excellent in strength and toughness, characterized in that it contains 0.8%, the balance is Al and inevitable impurities, and crystallized substances are spheroidized and dispersed in an alloy matrix. 2. Mg: 3.0-5.5%, Zn: 1.0-2.0%
(Mg / Zn: 1.5 to 5.5), Mn: 0.05 to 1.0%, C
An aluminum alloy containing u: 0.05 to 0.8% and Fe: 0.10 to 0.8%, the aluminum alloy consisting of the balance Al and unavoidable impurities is subjected to high pressure casting at a pressure of 50 to 150 MPa and is excellent in strength and toughness. Casting manufacturing method.