JP2790774B2 - High elasticity aluminum alloy with excellent toughness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly elastic aluminum alloy having excellent toughness, in particular, parts for automobiles and motorcycles, and various other structural parts, for example, cylinder liners and crankshaft bearings using conventional steel materials. The present invention relates to a highly elastic aluminum alloy having excellent toughness, which can be applied to a cap or the like and can be further thinned by being applied to a front fork of a motorcycle using an aluminum alloy.

[0002]

2. Description of the Related Art Lightening of structural parts is required from the viewpoint of increasing the efficiency of automobiles, two-wheeled vehicles, internal combustion engines, computers, and other various devices. However, these structural parts often place importance on rigidity. Therefore, a material having high rigidity is used as a constituent material. However, in order to obtain a material having high rigidity, a method of using a material having a high elastic modulus or a material having a large wall thickness is generally employed, which hinders weight reduction.

[0003] For example, it is necessary to use a steel material to satisfy the required rigidity for a crankshaft bearing cap of a motorcycle, so that it is difficult to reduce the weight. A front fork is made of an Al-Zn or Al-Si system. Although a material is used, thinning is limited in terms of elastic modulus.

On the other hand, recently developed quenching powder metallurgy is
For example, an aluminum alloy powder is made by an atomizing method in which a high-pressure fluid collides with a molten aluminum alloy to rapidly solidify and powderize the powder, and the obtained powder is formed into a compact having a density of 70 to 80% of the true density by cold isostatic pressing. Then, put it in a can, degas, form it by hot pressing or hot isostatic pressing (HIP), remove the can, and make it sufficiently dense by rolling, extrusion, etc., if necessary. The product is made by heat treatment.
e and alloy elements such as e can be dissolved at a high concentration, and a fine structure of crystal grains can be obtained.
It is possible to produce a highly elastic aluminum alloy material.

[0005] The rapidly solidified powdered aluminum alloy includes Al
There are -Si-based, Al-Fe-based, Al-Cu-based, and other various alloy systems, and various powder alloys have been developed so far. Among them, Al-Fe-based rapidly solidified powder materials containing Fe as a main alloy component and containing an appropriate amount of Si, Cu, etc. have excellent strength characteristics at room temperature and high temperature, so that they are used for heat-resistant parts such as engine parts. Application is being considered.

[0006] One of the inventors has previously stated that Fe: 4
-12%, Si: 1-4%, Cu: 1-6%, Mg: 0.3-3
%: V: 0.5-5%, Mo: 0.5-5% as required.
%, Zr: 0.4 to 4%, and a rapidly solidified powder material containing a total of 8% or less and a balance of Al and inevitable impurities was developed and applied for a patent. (JP-A-2-247348) This material has excellent strength and ductility at high temperatures up to 200 ° C. and is expected as a material for parts of internal combustion engines. If a defect is present, brittle fracture may occur depending on the use environment.

[0007]

SUMMARY OF THE INVENTION The present invention is based on the above-mentioned Al-Fe-based rapidly solidified powdered alloy, which has been previously developed. The purpose of the present invention is to provide an Al-Fe-based aluminum alloy having a high elastic modulus, excellent toughness, and good hot forgeability.

[0008]

In order to achieve the above-mentioned object, a highly elastic aluminum alloy having excellent toughness according to the present invention comprises Fe: 6 to 12%, Si: 1 to 4%, and V: 0.3
-3%, Cu: 0.3-3%, containing one or two of Zr and Mo in a total amount of 0.2-2%, with the balance being Al
And an aluminum alloy comprising unavoidable impurities,
Al-Fe-V-Si intermetallic compound satisfying the condition: 2.5≤ (Fe% + V%) / Si% ≤8, having a cubic lattice crystal structure in the structure and having an average particle size of 2 μm or less. Is a structural feature.

Further, Fe: 6 to 10%, Si: 1 to 3%, V:
0.3-2%, Cu: 0.3-3%, Zr and Mo
An aluminum alloy containing 0.2 to 2% in total of one or two of the above, and the balance being Al and unavoidable impurities, satisfying the following conditional expression: 4 ≦ (Fe% + V%) ≦ 8; Has a cubic lattice crystal structure with an average particle size of 2 μm
A second structural feature is that the following Al-Fe-V-Si-based intermetallic compound is dispersed, and the aluminum alloy is obtained by molding a rapidly solidified powder. The above is the third feature.

The significance of the addition of each component in the aluminum alloy of the present invention and the reason for the limitation will be explained. Fe is finely dispersed as an intermetallic compound containing Fe during rapid solidification to enhance the strength of the alloy, and to provide excellent toughness and elasticity. Give rate. If the Fe content is less than 6%, the effect is not sufficient, and if the Fe content exceeds 12%, the intermetallic compound becomes excessive in precipitation and impairs toughness. Therefore, the content range of Fe is 6 to
12% is preferred. More preferably, it is in the range of 6 to 10%.

Si contributes to the formation of intermetallic compounds and has strength,
Improve toughness and elastic modulus. If the content of Si is less than 1%, a sufficient effect cannot be obtained, and if it exceeds 4%, the intermetallic compound becomes excessive and the toughness is deteriorated. Therefore, the content range of Si is preferably 1 to 4%. More preferably, it is in the range of 1 to 3%. V also contributes to the formation of intermetallic compounds like Si, and improves the strength, toughness and elastic modulus of the alloy. However, if the content is less than 0.3%, the effect is not sufficient. The compound becomes excessive and deteriorates toughness.
Therefore, the content range of V is preferably 0.3 to 3%. More preferably, it is in the range of 0.3 to 2%.

When Cu is contained in the range of 0.3 to 3%,
The Al-Fe-V-Si intermetallic compound is likely to be stably present in the alloy structure. In addition, a part of Cu forms a solid solution,
Improves hot workability and strength. Zr and Mo contribute to improving the strength and elastic modulus of the alloy. The preferred content range is in the range of 0.2 to 2% in total, and if the content exceeds 2%, the toughness of the alloy decreases.

According to the present invention, as described above, Fe, Si,
V and Cu as essential components, and Z as a selective component
r and Mo are added, but the contents of Fe, V and Si are determined by the following conditional expression: 2.5 ≦ (Fe% + V
%) / Si% ≦ 8 is an essential requirement,
Al-F which gives toughness and high elastic modulus to alloy material under these conditions
A preferable dispersion state of the eV-Si-based intermetallic compound is obtained. If the value of (Fe% + V%) / Si% is less than 2.5, Si particles are precipitated and dispersed at the same time, and if it exceeds 8, Al-Fe intermetallic compounds are dispersed. Since these particles have a weak bonding force with the aluminum matrix and the particles themselves are brittle, the dispersion of these particles undesirably deteriorates the toughness of the alloy.

It is essential that the Al-Fe-V-Si intermetallic compound has a cubic lattice crystal structure and an average particle size of 2 μm or less. Under these conditions, a predetermined strength, toughness and high elasticity are obtained. Rate is achieved. If the average particle size of the Al-Fe-V-Si based intermetallic compound exceeds 2 µm, the toughness of the alloy tends to deteriorate. A more preferred range of the value of (Fe% + V%) / Si% is in the range of 4 to 8.

The preferred method for producing the aluminum alloy of the present invention will be described. The molten aluminum alloy having the above composition is rapidly solidified at a cooling rate of 10 ³ K / s or more by a rapid solidification method such as a gas atomization method or a single roll method. Powder. The obtained aluminum alloy powder is charged into an aluminum can after pre-compression, or directly charged into an aluminum can, and degassed in, for example, a vacuum. In the case of the aluminum alloy powder of the present invention, the temperature of the degassing treatment is
A temperature range of 400 to 500 ° C. is preferable. If the temperature is lower than 400 ° C., the degassing effect is not sufficient and the toughness is reduced. If the temperature exceeds 500 ° C., the intermetallic compound in the alloy structure becomes coarse and the strength and toughness are deteriorated. The degassing treatment may be performed by evacuation for a short time after heating in air.

Next, the solidification, molding and densification treatments are carried out by extrusion or forging, and the toughness is improved by giving a metal flow. Extrusion and forging are preferably performed at a processing temperature of 300 to 500 ° C. Processing temperature is 30
If the temperature is lower than 0 ° C., the deformation resistance of the alloy is large, and the working becomes difficult. In the case of extrusion, the extrusion ratio is preferably 4 or more. If the extrusion ratio is less than 4, the bonding between the powders becomes insufficient and the toughness is reduced. A billet for extrusion or forging can also be manufactured by using a spray forming method in which a rapidly solidified aluminum alloy powder is sprayed onto a substrate to directly manufacture a billet.

[0017]

In the present invention, specific amounts of Fe, Si, V and Cu are contained as essential components, Zr and Mo are selectively added, and the content range of Fe, V and Si is determined by a predetermined relational expression. The strength and toughness are limited by a combination of components and a systematic structure in which an Al-Fe-V-Si-based intermetallic compound having a crystal structure of a cubic lattice and an average particle size of 2 μm or less is dispersed in an alloy structure. As a result, the modulus of elasticity is increased, and material properties with excellent rigidity can be obtained.

[0018]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example Table 1 was obtained by the air atomization method (cooling rate of 10 ³ to 10 ⁴ k / s).
An aluminum alloy powder having the composition shown in Table 1 was produced. The obtained powder was classified into 150 μm or less, filled in an aluminum container having a diameter of 90 mm × 200 mm, and subjected to vacuum degassing at a temperature of 450 ° C., and the powder was sealed in the aluminum container. This was extruded at a temperature of 420 ° C. into a round bar having a diameter of 25 mm, and the powder was solidified, molded and densified. (Fe% + V%)
Table 1 shows the value of / Si%, the crystal structure of the Al-Fe-V-Si-based intermetallic compound, and the average particle size.

[0019]

[Table 1] << Table Note >> ○: Most of intermetallic compounds (Al-Fe-V-Si) are cubic lattice

The round bar obtained by extrusion was measured for tensile strength, and a notch tensile test according to ASTM-E602 and a Charpy impact test according to JIS Z 2202 were performed to evaluate toughness. Further, the longitudinal elastic modulus was measured by an ultrasonic method, and the critical upsetting ratio at 450 ° C. was measured in order to evaluate the hot workability. Table 2 shows the results. As shown in Table 2, all of the aluminum alloys according to the present invention exhibited excellent values in strength, toughness, and elastic modulus.

[0021]

Comparative Example An aluminum alloy powder having the composition shown in Table 3 was produced by the same air atomizing method as in Example 1, and this powder was treated in the same process as in Example 1 to obtain a round bar having a diameter of 25 mm. Obtained.
About the obtained round bar material, the tensile strength was measured in the same manner as in Example 1, a notch tensile test and a Charpy impact test were performed, and the longitudinal elastic modulus and the limit upsetting rate were measured. Table 4 shows the results. Those that are outside the conditions of the present invention are underlined.

[0023]

[Table 3] << Table Notes >> ○: Most of intermetallic compounds (Al-Fe-V-Si) are cubic lattices ×: No or small amount of cubic lattices

[0024]

[Table 4]

As can be seen from Table 4, the alloys outside the limits of the alloy composition of the present invention and those out of the conditions of the texture were
In particular, a satisfactory value in toughness has not been obtained. Alloy material No. 8 has a low Si content, and (Fe + V) / S
Since the value of i (conditional expression) exceeds 8, the Al-Fe-based compound precipitates at the same time, the toughness deteriorates, and the notch tensile strength decreases. The alloy material No. 9 has a high Fe content and the value of the conditional expression exceeds 8, so that the Al-Fe-V-Si-based intermetallic compound is excessively generated and the Al-Fe-based compound is also precipitated. The toughness is impaired, and the Charpy impact value and the notch tensile strength decrease. Since alloy material No. 10 has a high V content,
Excessive precipitation of the intermetallic compound impairs the toughness and lowers the Charpy impact value and the notch tensile strength. Alloy material N
In the case of o.11, a sufficient elastic modulus cannot be obtained because the content of Fe is small.

In the alloy material No. 12, since the value of the conditional expression is less than 2.5, Si particles are simultaneously precipitated to deteriorate toughness and lower the Charpy impact value. Since alloy material No. 13 has an excessive amount of Si and the value of the conditional expression is less than 2.5, excessive intermetallic compounds are generated and Si particles are simultaneously precipitated to impair toughness, resulting in low Charpy impact value. Become. Alloy material N
In the case of o.14, since the amount of Cu was excessive, stable precipitation of intermetallic compounds could not be obtained, the toughness was reduced, and the Charpy impact value was lowered. Alloy material No. 15 has too high a content of Zr + Mo, so that the toughness is reduced, and the Charpy impact value and the notch strength are reduced. Since the alloy material No. 16 has a small amount of Cu, the hot workability is inferior and the limit swaging ratio is low. Alloy material No.17 is V
, The strength is not sufficient, and the Charpy impact value is low. Since alloy material No. 18 does not contain Zr and Mo, both strength and toughness are not sufficient. Alloy material No.1
9, No. 20 has low Charpy impact value and notch tensile strength because it contains Mg.

[0027]

As described above, according to the present invention, an aluminum alloy material having excellent toughness and a high elastic modulus is provided, particularly as a front fork of a motorcycle, a crankshaft bearing cap, a connecting rod, and other mechanical structural members. Useful.

Claims (3)

(57) [Claims] 1. Fe: 6 to 12%, Si: 1 to 4 on a weight basis
%, V: 0.3 to 3%, Cu: 0.3 to 3%, an aluminum alloy containing 0.2 to 2% in total of one or two of Zr and Mo, and the balance being Al and unavoidable impurities. And the conditional expression, 2.5 ≦ (Fe% + V%) / S
i% ≦ 8, and the structure has a cubic lattice crystal structure and an Al-Fe-V-Si intermetallic compound having an average particle size of 2 μm or less dispersed therein. Excellent high modulus aluminum alloy. 2. Fe: 6 to 10%, Si: 1 to 3 based on weight.
%, V: 0.3 to 2%, Cu: 0.3 to 3%, an aluminum alloy containing 0.2 to 2% in total of one or two of Zr and Mo, and the balance being Al and unavoidable impurities. And the conditional expression, 4 ≦ (Fe% + V%) / Si
% ≦ 8, excellent in toughness characterized by the fact that an Al—Fe—V—Si based intermetallic compound having a crystal structure of cubic lattice in the structure and having an average particle size of 2 μm or less is dispersed. High elasticity aluminum alloy. 3. A highly elastic aluminum alloy having excellent toughness, wherein the aluminum alloy according to claim 1 is obtained by molding a rapidly solidified powder.