JPH0734169A - Wear resistant aluminum alloy excellent in strength - Google Patents

Abstract

PURPOSE:To enhance the strength of a wear resistant Al alloy used for the sliding parts of an air conditioner, etc., without deteriorating the elongation or wear resistance of the Al alloy. CONSTITUTION:This wear resistant Al alloy consists of 8-12% Si, 1.5-4% Cu, 0.2-1.0% Mg, 0.05-0.6% Mn, 0.01-0.1% Sr, <=0.1% Ti, 0.05-0.3% Cr and/or 0.05-0.25% Zr and the balance Al with inevitable impurities, has excellent wear resistance and elongation characteristics and also has much higher strength than a conventional material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear resistant aluminum alloy which is excellent in strength, elongation and wear resistance and is suitable as a material for sliding parts of air conditioners.

[0002]

2. Description of the Related Art Sliding parts such as cylinders and pistons in air conditioners and industrial equipment have excellent wear resistance and high strength as well as excellent elongation characteristics. Is required. From such a viewpoint, conventionally, an Al-Si-based eutectic alloy (JIS 4032 alloy) containing 11 to 13.5 wt% of Si has been widely used as the material for the component.

By the way, in recent years, the demands for weight reduction and high performance of the above-mentioned equipment have become more severe, and the materials used therefor have been further improved while maintaining good wear resistance and elongation characteristics. There is a strong demand for ensuring high strength. However, the above-mentioned conventional aluminum alloy (JIS 4032 alloy) cannot meet such a demand at present. In addition, JP-A-4-272149
Japanese Patent Publication No. 4-57738 discloses an aluminum alloy obtained by improving a conventional material, but it does not have sufficient strength to meet the above-mentioned requirements, and has a balance of strength, elongation property and wear resistance. There is a problem that is not maintained.
The present invention has been made in the background of the above circumstances,
While maintaining the excellent elongation characteristics of aluminum alloy,
The purpose of this is to improve the strength as well as the wear resistance.

[0004]

In order to solve the above problems, the aluminum alloy of the present invention contains Si: 8 to 12 wt.
%, Cu: 1.5-4 wt%, Mg: 0.2-1.0 w
t%, Mn: 0.05 to 0.6 wt%, Sr: 0.01
.About.0.1 wt%, Ti: 0.1 wt% or less, Cr: 0.05 to 0.3 wt%, Zr: 0.05
It is characterized in that it contains one or two of 0.25 wt% and the balance consists of Al and unavoidable impurities.

[0005]

The reason for limiting the alloy composition of the alloy of the present invention will be explained below together with its function. Si: 8 to 12% (hereinafter wt% is simply referred to as%) Si is added for the purpose of improving wear resistance. However, if Si is less than 8%, the wear resistance is insufficient, and
If it exceeds 0.1%, a large amount of coarse primary crystal Si is generated and the workability is deteriorated, so the above range is set.

Cu: 1.5-4% Cu enhances strength and at the same time improves wear resistance,
If it is less than 1.5%, its effect is small, and if it exceeds 4%, the eutectic Si is coarsened, the elongation is lowered, and the corrosion resistance is also lowered. Mg: 0.2-1.0% Mg is also added to improve the strength, but if it is less than 0.2%, its effect is small, and if it exceeds 1.0%, it does not contribute much to the strength. On the contrary, the workability is lowered, so the above range is set.

Mn: 0.05 to 0.6% Mn enhances strength and wear resistance, and further reduces deterioration of elongation when Fe impurities are large. However, 0.05%
If less than 0.6%, the effect is small, and if over 0.6%, Mn
Since a coarse intermetallic compound containing is crystallized to reduce the workability, the above range is set. Sr: 0.01-0.1% Sr is added for the purpose of refining eutectic Si to improve mechanical properties such as strength and elongation. If the Sr content is less than 0.01%, the effect is insufficient, and if the Sr content exceeds 0.1%, a coarse intermetallic compound containing Sr is crystallized and the workability is deteriorated.

Ti: 0.1% or less Ti is added to prevent casting cracks during casting and to further refine the crystal grains. However, if added in excess of 0.1%, coarse crystallized substances are generated and cold workability deteriorates, so the upper limit was made 0.1%. Cr: 0.05-0.3%, Zr: 0.05-0.25
% Cr and Zr have the effect of improving strength and wear resistance,
Further, since it has an effect of promoting the effect of Mn, it is selectively added. However, if it is less than 0.05%, the effect is insufficient, and if it exceeds 0.3% in Cr and 0.25% in Zr, coarse crystallized substances are generated and the workability is deteriorated. And

When manufacturing a member from the above-mentioned aluminum alloy of the present invention, a molten metal made of this alloy is semi-continuously cast, and the aluminum alloy ingot is homogenized at a temperature of 460 to 540 ° C. for 1 hour or more. 400 ~ 50 after applying
It is desirable to perform extrusion processing at a temperature of 0 ° C. with an extrusion ratio of 6 or more, followed by forging, solution treatment, quenching, and artificial aging treatment. In the above-mentioned step, homogenizing the aluminum alloy ingot, in addition to the usual purpose of homogenizing microsegregation and improving mechanical properties and workability, makes eutectic Si spherical and improves machinability. This is because. If the homogenization temperature is less than 460 ° C, the effect is insufficient and it is 540 ° C.
If it exceeds the range, eutectic melting may occur.

The reason why the extrusion process is carried out thereafter is to change the cast structure into a processed structure. However, if the extrusion temperature is less than 400 ° C., the deformation stress at the time of extrusion is large and the extrusion is difficult,
If the temperature exceeds 00 ° C, processing heat is generated, which may cause eutectic melting. Further, conventionally, the cast structure remains partially in the metal structure of the portion having the workability of less than the extrusion ratio 6, and the workability of the material is poor. Therefore, it is necessary to change the casting structure into a processed structure by forging after extruding at an extrusion ratio of 6 or more.

[0011]

EXAMPLES Examples of the present invention will be described below. (Example 1) Inventive alloys and comparative alloys having the compositions shown in Tables 1 and 2 were prepared, and each alloy was 228 mm by semi-continuous casting method.
After being cast into a billet having a diameter, homogenized at 570 ° C. for 12 hours, heated to 450 ° C. and hot extruded into a round bar having a diameter of 80 mm. After that, it was machined into a cylindrical shape with a diameter of 80 mm and a height of 40 mm, and upsetting was forged to a height of 20 mm at 420 ° C. using a 1000 ton hydraulic press, and 5
Immediately after solution treatment at 20 ° C. for 1 hour, water quenching is performed to 170
T6 treatment (aging treatment) was carried out at ° C x 8 hours.

[0012]

[Table 1]

[0013]

[Table 2]

Samples were taken from the above materials and evaluated for tensile strength, proof stress, elongation and wear resistance. That is, the tensile strength, yield strength and elongation were determined using the tensile test pieces of the cut out samples. The wear resistance was compared by determining the specific wear amount using an Ogoshi-type wear tester. FC25 was used for the abrasion element, and the load was 2.1 kg and the friction speed was 2.0 m / s. Further, in order to evaluate the cold forgeability, which is the most problematic in terms of workability, the extruded rod after the hot extrusion was subjected to the O material treatment at 410 ° C. for 2 hours, and then the 30 mm diameter × 30 mm height was obtained. It was machined into a cylinder, and was set up to a height of 10 mm using a 300 ton hydraulic press without lubrication, and the presence or absence of cracks was examined.

The results of each of the above tests are shown in Tables 3 and 4. The alloy of the present invention has a tensile strength of 44 kgf / mm ² or more and a yield strength of 34 kg.
It secured f / mm ² or more and realized an elongation value of 6% or more.
Also, it is superior in wear resistance to any of the comparative alloys. That is, the alloy of the present invention, compared to the comparative alloy,
Along with achieving higher strength, strength, elongation characteristics,
A good balance of wear resistance is maintained. Further, in the invention alloy, while all of them are excellent in cold forgeability,
Many materials cracked in the comparative alloys.

[0016]

[Table 3]

[0017]

[Table 4]

[0018]

As described above, the alloy of the present invention contains S
i: 8-12 wt%, Cu: 1.5-4 wt%, Mg:
0.2-1.0 wt%, Mn: 0.05-0.6 wt
%, Sr: 0.01 to 0.1 wt%, Ti: 0.1 wt
% Or less, and Cr: 0.05 to 0.3 wt
%, Zr: 0.05 to 0.25 wt% of 1 type or 2 types are contained, and the balance consists of Al and unavoidable impurities, so that excellent strength, elongation value and wear resistance are obtained, and A material suitable for sliding parts such as pistons can be obtained. Further, due to the above excellent characteristics, it is possible to easily cope with weight reduction and high performance of these parts.

Claims (1)

[Claims] 1. Si: 8 to 12 wt%, Cu: 1.5 to
4 wt%, Mg: 0.2 to 1.0 wt%, Mn: 0.0
5 to 0.6 wt%, Sr: 0.01 to 0.1 wt%, T
i: 0.1 wt% or less, further Cr: 0.0
5 to 0.3 wt% and Zr: 0.05 to 0.25 wt%, containing 1 or 2 types, the balance being Al and unavoidable impurities, and having excellent strength, wear-resistant aluminum alloy