JPH0118980B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has particularly excellent wear resistance and machinability.
Concerning Al-Si-Cu based high silicon aluminum alloys. In this specification, all "%" regarding alloy components indicate "% by weight". Hitherto, as this type of wear-resistant aluminum alloy material, Al--Si based aluminum alloy castings such as AC3A, AC8A-C, AC9A-B, etc. containing about 10 to 24% Si are well known. However, since these aluminum alloy materials are cast, the primary crystal grains of Si, which contribute to improving wear resistance, are generally coarse, including large particles with a particle size of approximately 150 μm. Moreover, since the dispersion is non-uniform, there is a drawback that the wear resistance of the material varies widely. Moreover, when this type of wear-resistant alloy is manufactured into a desired product by cutting the casting, the eutectic Si particles that are crystallized during casting are also relatively large and acicular. Because of the shape, the machinability is generally poor, and the life of the cutting tool is particularly short. On the other hand, in recognition of the above-mentioned drawbacks, various studies have been conducted to refine primary Si particles and eutectic Si particles, and one of the results is shown in Japanese Patent Publication No. 53-20242, etc. By making the cooling rate of the molten metal extremely rapid at 50°C/sec during casting, the growth of crystallized substances is suppressed, and the particle sizes of primary Si and eutectic Si are made extremely fine. It is proposed that That is, according to this prior art, the primary Si particles are
It has been reported that most of the eutectic Si particles can be made to have a maximum length not exceeding 20μ. However, according to the research of the present inventor, making the primary Si particles in the alloy structure as small as possible does not necessarily improve the wear resistance of the alloy proportionally. I found out that this is not the case. In other words, the wear resistance of the alloy is, of course, achieved by the individual crystallized Si particles absorbing the surface pressure during friction, but if the Si particles are too fine in the matrix, It has been inferred from many experimental results that the ability to absorb surface pressure during friction decreases, and as a result, it cannot contribute to the improvement of wear resistance as much as expected. . Therefore, based on this knowledge, this invention developed primary crystal Si that can contribute to the maximum improvement of wear resistance.
This was accomplished by investigating the particle size distribution of particles and eutectic Si particles. Therefore, the object of the present invention is to provide a high-silicon aluminum alloy containing Si in the hypereutectic region, which has extremely excellent wear resistance and machinability by controlling the alloy components and the alloy structure. The object of the present invention is to provide an aluminum alloy extruded material that has good properties and excellent workability. For the above purpose, this invention provides Si12~30
%, Cu0.3~7.0%, or even Mg0.3~
2.0%, the remainder consists of aluminum and unavoidable impurities, and in the case where the primary Si particles in the alloy structure belong to the particle size range of 40 to 80μ, they account for more than 60% of the total primary Si particle area, and Crystalline Si particles account for 60% or more of the total eutectic Si particle area in those with a particle size of 10μ or less, and the primary and eutectic Si particles mentioned above
The present invention provides a wear-resistant aluminum alloy extruded material characterized by uniformly dispersed particles. The aluminum alloy extrusion material according to the present invention may contain various other significant additives in addition to the above-mentioned components. The alloy having the above-mentioned structure according to the present invention is generally manufactured by hot extruding an ingot cast by a known casting method. These manufacturing conditions also affect the properties of the alloy, but in this invention, the components and structure of the resulting alloy are specified. First, the reason for limiting the range of each component of the alloy according to the present invention will be explained. As is well known, Si is effective as a component for improving wear resistance, and if it is less than 12%, the wear resistance will be poor. On the other hand, if it is contained in excess of 30%, casting will be impaired. It becomes difficult. The alloy according to the invention is directed to a high-silicon aluminum alloy containing Si in the hypereutectic region. The eutectic point in a two-element aluminum-silicon alloy exists at 11.7% silicon, but when a third element is added, the eutectic point shifts. Therefore, the alloy according to the present invention is required to contain at least 12% or more of Si in the hypereutectic region. The most suitable Si content is in the range of about 16 to 20%. Both Cu and Mg contribute to improving the strength of the alloy, and if it is less than 0.3%, the effect is insufficient. However, when Cu exceeds 7%,
Corrosion resistance deteriorates significantly. Moreover, when Mg exceeds 2%, the above-mentioned effects are not particularly enhanced, but rather coarse crystallized substances are formed and the mechanical properties are deteriorated. The most suitable Cu content obtained from the experimental results is
It is approximately 3 to 6%, and the Mg content is
It is about 0.45-0.65%. Preferably, for example, Sr and/or P may be added as other optional additive elements. All of these elements are equivalent in that they act as refining agents to refine primary Si particles during casting, and it is sufficient to contain at least one of them, but if each is less than 0.005%, the above effects will not be achieved. Even if it exceeds 0.1%, no significant effect can be expected. Furthermore, Ni, Fe, and Mn can be mentioned as other optional additive elements. All of these elements effectively contribute to improving the heat resistance of the alloy, and from the viewpoint of this effect, it is sufficient that they are equivalent and contain at least one or two or more of them. If the content is less than 0.5%, it is difficult to achieve the above effects, and if the content exceeds 3%, the machinability becomes extremely poor. The alloy extruded material according to the present invention having the above-mentioned component range is produced through a casting and then extrusion process in order to control its structure within a specific range. That is, first, the above aluminum alloy is produced into an aluminum alloy ingot by melting and casting according to a conventional conventional method. The primary Si particles contained in the ingot obtained by this casting process can be made finer to some extent by the addition of Sr and/or P, but the particle size is still 100 μm.
The total size is still quite large, including some that reach m. In addition, eutectic Si particles also have a particle size of
They are quite large as a whole, including about 30 μm, and their shape is needle-like. Therefore, these relatively coarse primary and eutectic Si
The ingot containing the particles is further extruded at a temperature of about 350 to 420°C. Then, through this hot extrusion, a part of the coarse primary Si particles contained in the alloy is destroyed, and almost all of them have a particle size in the range of 10 to 80 μm, and all of the particles with a size of 40 μm or more are primary Si particles. In addition to miniaturizing the area to a range that occupies more than 60% of the area and making the distribution uniform, eutectic
Si particles also divide needle-like crystals into granular shapes in the length direction, and almost all of them have a particle size of 15 μm.
In the range of less than m, and particles of less than 10 μm are all eutectic.
It shall be made so fine that it occupies an area ratio of 60% or more to the area of the Si particles. In the above, "almost all" means that it is possible to include particles that deviate from the above particle size range in extremely rare cases.
If preferable manufacturing conditions are adopted, there may be virtually no primary Si particles or eutectic Si particles outside the above particle size range. Such preferable manufacturing conditions are particularly as extrusion conditions: billet temperature: 350-420°C, ram speed: 0.03-0.2 m/min, extrusion ratio: 10-40, and more preferably extrusion die For example, use of a bearing with a length of 5 to 15 mm is recommended. By the way, when the grain size of primary Si particles in the alloy structure is in the range of 40 to 80 μm, 60%
The area ratio above is limited to:
If it contains a lot of particles smaller than 40μ, the desired excellent wear resistance cannot be obtained, and conversely, if it contains a lot of coarse particles with a diameter exceeding 80μ, the distribution becomes uneven and rough, resulting in poor wear resistance. This is because it increases the variation in wearability and reduces machinability. In addition, the eutectic Si particles have a particle size of 15μ or less and 10μ
The reason why it is limited to containing the following in an area ratio of 60% or more is that by controlling the particle size of the primary Si particles within the above range, they will inevitably be refined to the above range. If we were to point out the effect, at least when many eutectic Si particles remain as coarse particles exceeding 15μ, it is expected that defects will arise in machinability at least, and therefore, On the other hand, the effect of improving machinability can be mentioned. Examples Examples of the present invention will be shown below.

[Table] Regarding the aluminum-based alloy having the composition shown in Table 1 above, in the present invention, the alloy is first made into a billet with a diameter of 120 mm by melting and semi-continuous casting, and then this billet is extruded at an extrusion temperature of 415°C. The test piece was extruded into a round bar with a diameter of 30 mm at a ram speed of 0.1 m/min. In the test piece of the present invention material, all of the primary Si particles contained therein belong to the particle size range of 10 to 80μ, and it is clear that 40 to 80% of the primary Si particles are 60% of the total primary Si particle area. % or more of the area. And the eutectic Si particles are also refined,
All of them are in the particle size range of at least 15μ or less,
More than 60% of the total area of the eutectic Si particles was occupied by particles with a size of 10 μm or less. On the other hand, comparative material No. 6 was prepared at a cooling rate of 90°C/100°C according to the prior art shown in Japanese Patent Publication No. 53-20242.
_T6 treatment (510
℃×5 hours, 80℃ hot water quenching treatment and tempering treatment at 170℃×10 hours) was used as a test piece. Almost all of the primary Si particles contained in the alloy of comparative material No. 6 are extremely fine particles with a particle size of 40 μm or less. Moreover, Comparative Example No. 7 is a known AC8A alloy, and a commercially available product thereof was used as a test piece. The wear resistance and machinability of the various aluminum alloy materials mentioned above were compared with as-cast billets with the same composition as the materials of the present invention, and the results were as shown in Table 2 below. Ta.

【table】

[Table] As can be seen from the above wear resistance test results, the aluminum alloy material manufactured by the present invention has clearly superior wear resistance compared to as-cast materials. , the effect of reducing the variation is recognized, and the wear resistance is significantly superior to that of comparative materials. On the other hand, in a comparison of cutting tool life, the material of the present invention shows a remarkable improvement effect compared to the as-cast material, and shows excellent machinability that is equal to or better than the comparative material. I understand that.

Claims (1)

[Claims] 1 In an alloy containing 12 to 30% Si and 0.3 to 7.0% Cu, with the remainder consisting of aluminum and unavoidable impurities, and in which the primary Si particles in the alloy structure belong to a particle size range of 40 to 80μ. Occupies 60% or more of the total primary Si particle area, and in the case of eutectic Si particles with a particle size of 10μ or less, accounts for 60% or more of the total eutectic Si particle area, and the primary and eutectic Si particles are uniform. A wear-resistant aluminum alloy extruded material characterized by being dispersed in 2 Contains 12 to 30% Si, 0.3 to 7.0% Cu, and 0.3 to 2.0% Mg, with the balance consisting of aluminum and unavoidable impurities, and the primary Si particles in the alloy structure have a particle size of 40 to 30%.
Those in the 80μ range account for more than 60% of the total primary Si particle area, and eutectic Si particles have a particle size of 10μ.
A wear-resistant aluminum alloy extruded material, which accounts for 60% or more of the total eutectic Si particle area and is characterized in that the primary and eutectic Si particles are uniformly dispersed in the following: