JPH108161A - Al-Si alloy powder hot forging member - Google Patents

Abstract

(57) Abstract: An Al-Si alloy powder hot forged member is provided. SOLUTION: Si: 8 to 16%, Fe: 3 to 12%,
A composition containing Ni: 1 to 2.9% and Cr: 0.5 to 3%, with the balance being Al, and an intermetallic compound particle and an Si particle having an average particle diameter of 0.01 to 1 μm in the base material. Al-Si-based alloy powder (a powder) having a structure in which is dispersed and having an average particle diameter of 10 to 40 μm, and Si: 25 to 40
%, Fe: 3 to 8%, Ni: 1 to 6%, Cr: 0.5 to
A composition containing 3%, with the balance being Al, and an average particle diameter having a structure in which intermetallic compound particles having an average particle diameter of 0.01 to 1 μm and Si particles having an average particle diameter of 5 to 10 μm are dispersed in the base material. A hot forged member with an Al-Si alloy powder (b powder) of 30 to 60 µm, wherein the average particle diameter of the b powder is larger than the average particle diameter of the a powder, and the b powder is Al-Si 10 to 40% by volume is dispersed in the hot forged member of the base alloy powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structural member of a mechanical device, particularly to an Al-Si alloy powder hot cast member suitable for use as a gear member of an oil pump.

[0002]

2. Description of the Related Art Conventionally, rotors and impellers, which are parts of fluid machines such as oil pumps and hydraulic turbines, are manufactured by rapidly forging rapidly solidified Al-Si alloy powders. A hot forging member of a system alloy powder is used. As the hot forging member of the Al-Si alloy powder, for example, those described in Japanese Patent Publication No. 20215/1992 and JP-A-4-314983, and others % By weight, Si: 6 to 22%, Fe: 3 to
A composition containing 12%, Ni: 1 to 2.9%, and Cr: 0.5 to 3%, with the balance consisting of Al and inevitable impurities; Rapidly solidified Al-Si having a structure in which eutectic and / or precipitated Si is dispersed and having excellent cavitation damage resistance
A hot forged member of a system alloy powder has also been proposed (see Japanese Patent Application Laid-Open No. 7-292431).

[0003]

On the other hand, in recent years, the output and the size of the above fluid machines have been remarkably increased, and accordingly, the rotational motion of structural members such as rotors and impellers in these fluid machines has also become faster. (Bubbles) generated in the periphery of the structural member in proportion to
Although the shock wave generated by the rupture of the aluminum alloy is also in a state of increasing strength, in the above-mentioned conventional Al-Si alloy powder hot forged member,
Each of them has a structure in which primary crystal Si is dispersed in the base material, and the base material is relatively soft with respect to the primary crystal Si, so that the base portion of the member surface is damaged by the shock wave (cavitation damage). When the shaft that drives the rotor is an iron-based material, such as when used for the inner rotor of an oil pump rotor consisting of an outer rotor and an inner rotor, the temperature rise during operation causes a difference in thermal expansion between the rotor and the shaft. There has been a problem that the clearance is increased, the wear between the rotor and the shaft is increased, and the pump performance is further reduced.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the viewpoints described above, A is excellent in cavitation damage resistance and wear resistance, and has a thermal expansion coefficient close to that of iron-based materials.
As a result of conducting research to develop a hot forging member of an l-Si alloy powder, two types of rapidly solidified Al-Si alloy powders having different Si contents and different average particle diameters were mixed in a predetermined ratio and hot forged. The Al-Si alloy powder hot forged member obtained by the above method is more excellent in cavitation damage resistance and wear resistance than the conventional Al-Si alloy powder hot forged member, and has a thermal expansion coefficient of iron-based material. The research result obtained that it was close to.

The present invention has been made on the basis of the above-mentioned research results, and in terms of% by weight (hereinafter,% indicates% by weight), Si: 8 to 16%, Fe: 3 to 12%, Ni:
1 to 2.9%, Cr: 0.5 to 3%, the remainder being A
1 and an unavoidable impurity, and an average particle diameter in the base material: an average particle diameter having a structure in which intermetallic compound particles and Si particles of 0.01 to 1 μm are dispersed;
μm Al-Si alloy powder (hereinafter referred to as a powder)
And Si: 25 to 40%, Fe: 3 to 8%, Ni: 1 to
6%, Cr: 0.5 to 3%, the balance being Al and unavoidable impurities, and the average particle size in the base material: 0.0
Intermetallic compound particles of 1 to 1 μm and average particle size: 5-1
Average particle size having a structure in which Si particles of 0 μm are dispersed: 3
Al-Si obtained by hot forging a mixed powder with an Al-Si alloy powder (hereinafter referred to as b powder) of 0 to 60 µm.
A hot forged member of a system alloy powder, wherein the b powder has an average particle diameter larger than that of the a powder, and the b powder is dispersed in the Al-Si alloy powder hot forged member by 10 to 40% by volume. Al-Si based alloy powder hot forging member.

Next, the reason for limiting the composition of the Al-Si alloy powder hot forged member of the present invention as described above will be described. A component composition (a) Si The Si component forms Si particles that are finely dispersed in the matrix, and combines with Al, Fe, Ni, and Cr to form intermetallic compound particles that are also finely dispersed in the matrix. Has the effect of improving cavitation damage resistance, and coarse Si particles further improve wear resistance,
Increasing the Si component has the effect of lowering the coefficient of thermal expansion to approach the coefficient of thermal expansion of the iron-based material. However, if the content of Si in the a powder is less than 8%, the desired effect on the effect of improving the cavitation damage resistance can be obtained. On the other hand, if the content exceeds 16%, no further effect of improving cavitation damage resistance can be expected.
It was determined to be 6%. The more desirable range of the content of Si in the a powder is 10 to 14%. Further, if the content of Si in the b powder is less than 25%, a desired effect cannot be obtained in the action of improving the wear resistance. On the other hand, if the content exceeds 40%, the wear resistance is further improved. Since the effect cannot be expected, the content was determined to be 25 to 40%. The more desirable range of the content of Si in the b powder is 30 to 35%.

(B) Fe The Fe component has the effect of forming an intermetallic compound with Al, Si, and Cr to improve cavitation damage resistance as described above.
If the content is less than 12%, the desired effect of improving the cavitation damage resistance cannot be obtained. On the other hand, if the content exceeds 12%, the intermetallic compound particles become coarse and the cavitation damage resistance is improved. Since the effect cannot be expected, the content was determined to be 3 to 12%. In addition,
A more desirable range of the content of Fe in the a powder is 6
９9%. Further, if the content of Fe in the b powder is less than 3%, a desired effect cannot be obtained in the action of improving the resistance to cavitation damage, whereas if the content exceeds 8%, the toughness decreases. Its content is 3 ~
8%. The more desirable range of the content of Fe in the b powder is 3 to 6%.

(C) Ni The Ni component has an effect of forming an intermetallic compound with Al, Si, and Cr to improve cavitation damage resistance and an effect of improving toughness as described above. If the content of Ni in the a powder is less than 1%, the desired effect on the action of improving the cavitation damage resistance and toughness cannot be obtained, while if the content exceeds 2.9%, the intermetallic compound particles are coarse. Therefore, the effect of improving cavitation damage resistance cannot be expected, so the content was determined to be 1 to 2.9%. Note that a
A more desirable range of the Ni content in the powder is as follows.
5 to 2.5%. Further, if the content of Ni in the b powder is less than 1%, a desired effect cannot be obtained in the action of improving cavitation resistance, while if the content exceeds 6%, further improvement in toughness cannot be expected. Therefore, the content was determined to be 1 to 6%. The more preferable range of the Ni content in the b powder is 3 to 5%.
It is.

(D) Cr The Cr component forms a solid solution in the matrix to strengthen it, and also forms an intermetallic compound as described above and contributes to the spheroidization and miniaturization of the Cr component to prevent cavitation damage. However, if the content is less than 0.5%, the desired effect cannot be obtained, while the content is 3%.
Is exceeded, the intermetallic compound tends to coarsen in the same manner as in the case of Fe and Ni.
It was decided. Preferably, the content is 1.5 to 2.5%.

Structure and Average Particle Size of B Powder (e) Structure and Average Particle Size of a Powder The average particle size of the a powder is preferably in the range of 10 to 40 μm, more preferably 20 to 30 μm. In the base of the a powder, fine intermetallic compound particles and Si particles having an average particle diameter of 0.01 to 1 μm (preferably 0.1 to 0.5 μm) are formed, and the a powder is ,
It is formed when the Al alloy melt having the above composition is made into a powder by a powder production method of cooling at a cooling rate of 10 ⁴ ° C / sec or more accompanied by rapid solidification such as gas atomization. In the case of a powder production method which does not depend on the above conditions, the intermetallic compound particles and the Si particles are coarsened to exceed 1 μm even if the molten Al alloy having the above composition is used, and the desired excellent cavitation damage resistance and wear resistance are obtained. In addition, it is not possible to secure characteristics having a low coefficient of thermal expansion.

(F) Structure and average particle size of b powder The average particle size of b powder is preferably in the range of 30 to 60 μm, and more preferably 50 to 60 μm. Fine intermetallic compound particles having an average particle size of 0.01 to 1 μm (preferably 0.5 to 0.8 μm) and an average particle size of 5 to 10 μm (preferably 5 to 7 μm)
m) coarse Si particles are formed, and this b powder is obtained by a powder production method of cooling an Al alloy melt having the above composition at a cooling rate of 10 ⁴ ° C / sec or more accompanied by rapid solidification such as gas atomization. In the case of a powder production method which does not rely on rapid solidification, the intermetallic compound particles exceed 1 μm and have an Si content of more than 1 μm. The particles become coarser than 10 μm, and it is not possible to secure the desired properties of excellent cavitation damage resistance, abrasion resistance and a low coefficient of thermal expansion.

(G) Relationship between a-powder and b-powder The b-powder needs to have an average particle size larger than that of the a-powder, and the a-powder contains 10 to 40% by volume of the b-powder (preferably 25 to 25% by volume). (35% by volume). If the dispersion amount of the b powder is less than 10% by volume, sufficient wear resistance cannot be obtained, while the dispersion amount of the b powder is 40%.
Even if the dispersion exceeds the volume%, further improvement of the wear resistance cannot be expected, and the cavitation damage resistance is reduced and the toughness is also reduced. (Preferably 25 to 35% by volume).

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hot forging member of an Al-Si alloy powder according to the present invention will be described in detail with reference to examples. First, an Al alloy melt having the component composition shown in Table 1 is prepared by a normal melting method, and rapidly solidified by a nitrogen gas atomizing method at a predetermined cooling rate in a range of 10 ³ to 10 ⁵ ° C./sec. A1 having an average particle size shown in Table 1 by preparing an Al alloy powder and adjusting the particle size by sieving
~ A7 powder was produced. The average particle size of the intermetallic compound particles and Si particles dispersed in the matrix of the a1 to a7 powders was measured by a metallographic photograph, and the results are also shown in Table 1.

[0014]

[Table 1]

Further, an Al alloy melt having the component composition shown in Table 2 is prepared by a normal melting method, and rapidly cooled by a nitrogen gas atomizing method at a predetermined cooling rate in a range of 10 ³ to 10 ⁵ ° C./sec. Solidification was performed to obtain an Al alloy powder, and the particle size was adjusted by sieving to produce b1 to b7 powders having average particle sizes shown in Table 2. The average particle diameters of the intermetallic compound particles and Si particles dispersed in the matrix of the b1 to b7 powders were measured by a metallographic photograph.
It was shown to.

[0016]

[Table 2]

The powders a1 to a7 and the powders b1 to b7 shown in Tables 1 and 2 are blended in the proportions shown in Tables 3 and 4, mixed and pressed into a green compact at a pressure of 6 ton / cm ² . This green compact is heated at 450 ° C. in an argon atmosphere.
In a state where the Al-Si alloy powder hot forged member of the present invention (hereinafter referred to as “Hot forged member”) is heated for 30 minutes using a mold heated to 450 ° C. and hot forged at a pressure of 8 ton / cm ^2. 1-15 and Comparative A
Length: 10 mm, width: 10 mm, composed of l-Si alloy powder hot forged members (hereinafter referred to as comparative forged members) 1 to 8,
A block-on-ring test piece having a length of 40 mm was prepared. The thermal expansion coefficients of these block-on-ring test pieces were measured, and the results are shown in Tables 3 and 4.

Next, the block-on-ring test piece was rotated at a rotational speed of 5 m / sec. The lubricating oil was dripped onto the ring made of SCM420 rotating at a load of 20 kgf for 15 minutes, and the wear amount of the block-on-ring test piece was measured. The results are shown in Tables 3 and 4.

Further, a1 to a1 shown in Tables 1 and 2
The a7 powder and the b1 to b7 powders were blended in the proportions shown in Tables 3 and 4, mixed and pressed into a green compact at a pressure of 6 ton / cm ² , and the green compact was heated in an argon atmosphere at a temperature of 4:
While heating at 50 ° C. for 30 minutes, 450
Using a mold heated to 8 ° C. and performing hot forging at a pressure of 8 ton / cm ² , a shape conforming to the vibration type cavitation damage test method specified in ASTM Standard G32-85,
That is, an outer diameter having a central part of a diameter: 3 mmφ: 12 mm
φ × thickness: A 3 mm ring-shaped upper part and a test piece having a cylindrical lower part with a length of 7 mm concentrically and integrally formed with the ring-shaped upper part.
And the vibration type cavitation damage test piece which consists of comparative forging members 1-8 was manufactured, respectively.

The above-mentioned forged members 1 to 15 of the present invention and comparative forged members 1 to 8 are fixed to the center of the bottom of a water tank containing distilled water at 50 ° C., and a vibrator is positioned immediately above the tank. Vibrator amplitude: 35 μm, Vibration type cavitation damage test piece-vibrator distance:
Perform cavitation damage test under the conditions of 0.8 mm, test time: 1 hour, and after the test,
The volume loss of the vibration type cavitation damage test specimens composed of the forged members 1 to 15 of the present invention and the comparative forged members 1 to 8 was measured, and the measurement results are shown in Tables 3 and 4.

With respect to the forged members 1 to 15 of the present invention and the comparative forged members 1 to 8, the average particle diameter of the powder dispersed in the base material and the average particle diameter of the intermetallic compound particles and the Si particles in the powder were measured. However, the average particle diameters of the a1 to a7 powders and b1 to b7 powders shown in Tables 1 and 2 and the average particle diameters of the intermetallic compound particles and the Si particles in the powders were almost the same.

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

From the results shown in Tables 1 to 4, the thermal expansion coefficients of the forged members 1 to 15 of the present invention are close to the thermal expansion coefficient of an iron-based material (10 to 13 × 10 ⁻⁶ / ° C.), and the wear resistance is high. Al-Si alloy powder hot forging 1 to 8
As can be seen from any of the above, if any of the constituent components and the compounding ratio deviate from the scope of the present invention, the cavitation damage resistance or the abrasion resistance is reduced, and the progress of the wear is apparently promoted. . As mentioned above,
The Al-Si alloy powder hot forged member of the present invention has a coefficient of thermal expansion close to the coefficient of thermal expansion of an iron-based material, has excellent wear resistance, and has significantly improved cavitation damage resistance. Even when it is used as a structural member of a fluid machine, it exhibits excellent durability over a long period of time and makes it possible to extend the service life.

Claims (2)

[Claims] (1) In terms of% by weight, Si: 8 to 16%, Fe: 3 to 12%, Ni: 1 to 2.
9%, Cr: 0.5 to 3%, the balance being composed of Al and inevitable impurities, and intermetallic compound particles and Si particles having an average particle size of 0.01 to 1 μm in all, dispersed in the substrate. Al-Si alloy powder having an average particle size of 10 to 40 µm (hereinafter referred to as a powder) having a structure; Si: 25 to 40%; Fe: 3 to 8%; Ni: 1 to 6
%, Cr: 0.5 to 3%, the balance being Al and inevitable impurities, and the average particle size in the base material: 0.01
１1 μm intermetallic compound particles and average particle size: 5-10
Average particle size having a structure in which Si particles of μm are dispersed: 30
An Al-Si alloy powder hot-forged member obtained by hot forging a mixed powder with an Al-Si alloy powder (hereinafter, referred to as b powder) of about 60 µm, Al is characterized in that the diameter is larger than the average particle diameter of the a powder, and the b powder is dispersed in the Al-Si alloy powder hot forged member by 10 to 40% by volume.
-Si-based alloy powder hot forging member. 2. The hot-forged Al-Si alloy powder according to claim 1, wherein the a powder and the b powder are both rapidly solidified Al-Si alloy powders.