JP3184367B2 - Method for producing high toughness Al-Si alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-toughness Al-Si alloy, and more particularly, to a method of spraying a molten Al-Si alloy with a non-oxidizing gas and depositing it while rapidly solidifying it. The present invention relates to a method for producing a high-toughness Al-Si alloy using a billet to produce an extruded material suitable as a material for the automobile industry, home appliances and industrial machines.

[0002]

2. Description of the Related Art Aluminum materials are widely used as lightweight industrial materials. In recent years, in the fields of the automobile industry, home appliances and industrial machinery, various devices have been improved in performance and speed. Aluminum materials used as components of these devices are required to have better properties.

A powder metallurgy method utilizing a rapid solidification method is a method for imparting excellent properties to an aluminum material. The powder metallurgy method is a method in which an aluminum alloy material is finely powdered, compression-molded, and extruded, forged, or the like is processed to obtain a molded body. Compared to high temperature characteristics and abrasion resistance, they have been put to practical use in parts of automobiles and home electric appliances. However, in the case of a high-Si Al-Si alloy, it is easily oxidized, particularly in the process of rapid solidification and preforming, and Si or an intermetallic compound containing Si is easily crystallized or precipitated in a coarse manner. Is often reduced.

As a technique for solving the above-mentioned drawbacks, a method of obtaining a preformed body by spraying a molten metal with a non-oxidizing gas in a non-oxidizing atmosphere and depositing it on a collector while rapidly solidifying it (hereinafter referred to as spraying). Deposition)
Is being developed by OSPREYMETALS in the UK.
No. 62-1849). According to the spray deposition, the metal atomized by the non-oxidizing gas is immediately fused on the collector and rapidly cooled and solidified.
Alternatively, since the intermetallic compound containing Si is unlikely to become coarse, improvement in toughness of the material is expected.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies on combinations of material components and structures for further improving the characteristics of Al-Si alloy materials while taking advantage of spray deposition. It is an object of the present invention to provide a method for producing a high toughness Al-Si-based alloy which obtains an Al-Si-based alloy having excellent toughness and high-temperature strength by applying spray deposition.

[0006]

According to a first aspect of the present invention, there is provided a method for producing a high-toughness Al-Si alloy, comprising 10 to 30% of Si and one of Ti and B.
Spray deposition is performed by spraying a molten metal of an Al-Si based alloy containing at least 0.005 to 0.5% of a total of at least one species and the balance of Al and inevitable impurities with a nitrogen gas in a nitrogen atmosphere to rapidly cool and solidify. By performing the billet, the billet is extruded at an extrusion ratio of 3 or more,
Average grain size is 0.1-5 μm, average Si grain size is 1-10
An extruded material containing 0.03 to 0.2% of nitrogen and having a particle size of 0.03 to 0.2% is characterized in that the Al-Si alloy is made of Cu 0.5 to 6
%, And 0.2 to 3% of Mg. The method for producing a high-toughness Al-Si alloy according to claim 3, wherein the Al-Si alloy is one of Fe, Mn and Ni.
Or more, and the average particle size of the intermetallic compound of these alloying elements and Al and Si in the extruded material is 10 to 10%.
μm or less. Further, the method for producing a high-toughness Al-Si alloy according to claim 4 includes the above-described Al-Si alloy.
The Si-based alloy contains 0.2 to 2.0% of Zr, and the average particle size of the Al-Zr-based intermetallic compound in the extruded material is 10 µm or less.

[0007] Si contained as an essential component improves the wear resistance of the alloy. The preferred content is in the range of 10 to 30%. When the content is less than 10%, the effect is small, and when it exceeds 30%, the average diameter of the Si particles is increased even by spray deposition.
The average grain size exceeds 10 μm even after extrusion, and the fracture toughness is poor.

In the solidification process, Ti and B form TiB ₂
Borides or Al ₃ Ti to form such, because they become the grain nuclei, it is possible to refine the crystal grains. Preferably, Ti or B is contained alone, or both Ti and B are contained in a total amount of 0.005 to 0.5%. If the content is 0.005%, the effect is small, and if it exceeds 0.5%, the toughness of the alloy decreases.

[0009] Cu solidifies or age-precipitates in the alloy to increase the strength of the alloy. The preferred content range is 0.5 to 6.
%, The effect is small when it is less than 0.5%, and the corrosion resistance of the alloy is deteriorated when it exceeds 6%. Mg, like Cu, forms a solid solution or age-precipitated in the alloy to increase the strength of the alloy. The preferred content is in the range of 0.2-3%, 0.2%
If it is less than 3%, the effect is small, and if it exceeds 3%, the toughness of the alloy decreases.

[0010] Fe, Mn, Ni and Zr are Al-S
i-Fe, Al-Fe, Al-Mn, Al-Ni, Al
-Form an intermetallic compound such as a Zr-based compound to improve the high-temperature strength of the alloy. The preferred content range is 1-10% in total,
If the content is less than 1%, the effect is not sufficient. If the content exceeds 10%, the average grain size of these intermetallic compounds exceeds 20 μm, and the toughness of the alloy is reduced.

The atmosphere for performing spray deposition is a non-oxidizing gas atmosphere, and the gas for spraying the molten metal is also a non-oxidizing gas to prevent oxidation of the alloy. Oxygen is present as an oxide in the alloy and causes a decrease in toughness. However, when the content is less than 0.1%, substantially no problem occurs. . As the non-oxidizing gas, it is preferable to use helium gas (He), argon gas (Ar), or nitrogen gas (N ₂ ) alone or as a mixture. In particular, when the molten Al-Si alloy is sprayed using nitrogen gas, nitrides are formed in the alloy, and fine nitrides are dispersed in the extruded material, so that the high-temperature strength of the material can be improved. In this case, the preferred nitrogen content in the extruded material is 0.03-0.2
%. If it is less than 0.03%, the formation of nitrides is insufficient, and the effect of improving the high-temperature strength may not be obtained. If it exceeds 0.2%, the toughness of the alloy tends to decrease.

According to the spray deposition, the alloys atomized by the non-oxidizing gas as described above immediately fuse together on the collector and are rapidly solidified at an average cooling rate of 10 ² to 10 ⁴ ° C./sec. , Si particles and Al-Si-Fe
The system and other intermetallic compounds are refined and the crystal grains are refined. The Si particles and the intermetallic compound are further divided by the extrusion of the billet to improve the strength properties of the alloy. The average diameter of the Si particles in the finally obtained extruded material is preferably 1 to 10 μm, the average particle diameter of the intermetallic compound is 10 μm or less, and the average diameter of the crystal grains is preferably 0.1 to 5 μm. When these values are smaller than the lower limit, the strength of the alloy is not sufficient, and when it exceeds the upper limit, the toughness of the alloy is reduced.
In order to form the above alloy structure in combination with spray deposition, it is preferable to perform extrusion at an extrusion ratio of 3 or more, and if the extrusion ratio is less than 3, insufficient separation of Si particles and intermetallic compounds. These particles have a particle size of 20μ
m, which tends to degrade the fracture toughness of the alloy.

[0013]

The method for producing a high-toughness Al-Si alloy according to the present invention has the above-described structure, and has a specific range by a combination of a specific alloy composition and a process consisting of spray deposition-extrusion at an extrusion ratio of 3 or more. To form a metal structure having a Si particle diameter, an intermetallic compound particle diameter, and a crystal particle diameter, and the obtained alloy material has excellent toughness.

[0014]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example 1 An Al—Si alloy shown in Table 1 was melted, and a molten metal stream was sprayed with an argon gas or a nitrogen gas in an argon gas atmosphere or a nitrogen gas atmosphere, and deposited while being rapidly cooled and solidified on a columnar collector. Spray deposition was performed to produce a cylindrical billet having an outer diameter of about 260 mm and a length of 900 mm. This billet was extruded at an extrusion temperature of 400 ° C and an extrusion ratio of
Extrusion was performed at 3 to 12, and after the extrusion, the alloy containing Cu and Mg was subjected to heat treatment under the conditions of solution treatment (treatment temperature of 485 ° C.), water cooling, and artificial aging (175 ° C. × 6 hrs).
The extruded material and heat-treated material thus obtained are subjected to gas analysis to measure oxygen content and nitrogen content, measurement of crystal grain size, measurement of Si particles and particle size of intermetallic compound particles, and Fracture toughness was measured. Table 2 shows the measurement results. The fracture toughness was determined by ASTM E39
9 based on the rating.

As can be seen from Table 2, the alloy materials manufactured according to Example 1 were all Si particles and Al-S
i-Fe system, Al-Fe system, Al-Mn system, Al-Ni
Particle size of intermetallic compounds such as Al-Zr system
m and a fine crystal grain, and exhibited a room temperature fracture toughness sufficient for use as, for example, a piston for an internal combustion engine.

[0016]

[Table 1]

[0017]

[Table 2]

Comparative Example 1 Al-Si alloys shown in Table 3 were melted and spray-deposited in the same manner as in Example 1 to produce a cylindrical billet having an outer diameter of about 260 mm and a length of 900 mm. This billet was extruded at an extrusion temperature of 400 ° C. and an extrusion ratio of 2 to 12, and then heat-treated under the same conditions as in Example 1. About the obtained heat-treated material, the oxygen content, the nitrogen content, the crystal grain size, the average particle size of the Si particles and the intermetallic compound particles, and the room temperature fracture toughness were measured in the same manner as in Example 1. Table 4 shows the measurement results.

[0019]

[Table 3]

[0020]

[Table 4]

In Tables 3 and 4, those outside the conditions of the present invention are underlined. As can be seen from Table 4, Sample No. 1 has a low room temperature fracture toughness due to a small Ti content of 0.003%, and is difficult to use as a piston for an internal combustion engine, for example. No. 2 has Al-
The Ti-based intermetallic compound is coarsely crystallized and deteriorates the room temperature fracture toughness. In No. 3, since the content of B is large, the Al-B-based intermetallic compound is coarsely crystallized, and the room-temperature fracture toughness is reduced. No. 4 had an acidic atmosphere due to the use of air as the atmosphere gas for spray deposition, and the oxygen content in the obtained alloy material was as large as 0.3%, and the room-temperature fracture toughness was reduced. In No. 5, since the extrusion ratio in the extrusion process was low and hardly subjected to hot working, Si particles and the like remained coarse without being divided, degrading the fracture toughness. No.6
Since Si has a large Si content, the Si particle size becomes coarse, and the room-temperature fracture toughness is poor. In No. 7, since the total content of Fe, Mn, and Ni exceeds 10%, the grain size of the intermetallic compound of these elements and Al and Si is large, and the fracture toughness is reduced.

Example 2 Si 20%, Cu 2%, Mg 1%, Fe 5%, Ti 0.03%
Spraying in which an Al-Si alloy containing 0.01% and B and containing the balance of Al and unavoidable impurities is produced by changing the melting temperature, and the resulting molten metal is allowed to flow down in a nitrogen gas atmosphere and sprayed with nitrogen gas. Deposition, 260mm outside diameter, length
An 800 mm cylindrical billet was prepared. This billet
After extrusion at an extrusion ratio of 7 and an extrusion temperature of 400 ° C., heat treatment was performed under the conditions of solution treatment (treatment temperature: 485 ° C.-water cooling—artificial aging (175 ° C. × 6 hrs). The obtained heat-treated material was subjected to gas analysis. Measure oxygen and nitrogen content
The crystal grain size, the grain size of Si and the intermetallic compound were measured, and a fracture toughness test and a tensile test at 200 ° C. were performed. Table 5 shows the measurement results and test results.

Comparative Example 2 An Al—Si alloy having the same composition as in Example 2 was melted at 850 ° C., and the obtained molten metal was spray-deposited with an argon gas in an argon gas atmosphere to obtain an outer diameter of about 260 mm and a length of about 260 mm. A cylindrical billet having a length of 800 mm was produced. Further, an Al-Si alloy having the same composition as in Example 2 was melted at 1250 ° C,
The obtained molten metal was spray-deposited with a nitrogen gas in a nitrogen gas atmosphere to produce a billet having the above dimensions. These billets were subjected to hot extrusion-heat treatment under the same conditions as in Example 2. The obtained heat-treated material is subjected to gas analysis to measure oxygen and nitrogen contents, to measure crystal grain size, Si and intermetallic compound grain sizes, and to conduct a fracture toughness test and a tensile test at 200 ° C. Was. Table 5 shows the results.

[0024]

[Table 5]

As shown in Table 5, when comparing Sample Nos. 16 to 18 prepared according to Example 2 and Samples No. 8 and No. 9 prepared according to Comparative Example 2, for example, Sample No.1 using nitrogen as molten gas spray gas
The high-temperature tensile strength of Sample No. 8 using argon was 280 MPa while the high-temperature tensile strength of Sample No. 6 using argon was 320 MPa, and the high-temperature strength was improved when the molten metal was sprayed with nitrogen gas. Further, in Sample No. 9 in which the melting temperature was increased and a large amount of nitride was contained, the nitride became coarse and a decrease in room-temperature fracture toughness was observed.

[0026]

As described above, according to the present invention, there is provided an Al-Si alloy having excellent fracture toughness,
It can be expected to be applied as parts for home appliances and industrial machines.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI // C22C 21/02 C22C 21/02 (72) Inventor Naoki Tokishi 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal (56) References JP-A-4-182057 (JP, A) JP-A-64-57965 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 1 / 04-1/05 C22C 1/10 C22C 21/00-21/18 B22D 23/00 B22F 3/115

Claims (4)

(57) [Claims] (1) Si 10 to 30% (% by weight, the same applies hereinafter);
Depositing a molten Al-Si alloy containing at least one of Ti and B in a total content of 0.005 to 0.5%, the balance being Al and unavoidable impurities, by spraying with a nitrogen gas in a nitrogen atmosphere to rapidly solidify; The billet is extruded at an extrusion ratio of 3 or more to have an average crystal grain size of 0.1 to 5 μm and an average grain size of Si of 1 to 10 μm.
A method for producing a high-toughness Al-Si alloy, wherein the extruded material contains 0.03 to 0.2% of nitrogen . 2. The method according to claim 1, wherein the Al—Si alloy is Cu 0.5 to 6%,
The method for producing a high toughness Al-Si alloy according to claim 1, wherein the alloy contains 0.2 to 3% of Mg. 3. An Al—Si alloy containing at least one of Fe, Mn and Ni in a total of 1 to 10%, and an average of intermetallic compounds of these alloy elements and Al and Si in an extruded material. Wherein the particle size is 10 μm or less.
3. The method for producing a high toughness Al-Si alloy according to 1 or 2 . 4. The method according to claim 1, wherein the Al—Si alloy is Zr 0.2 to 2.0%.
The average particle size of the Al-Zr-based intermetallic compound in the extruded material is 10 µm or less.
4. The method for producing a high-toughness Al-Si-based alloy according to any one of items 1 to 3.