JPH1072649A - High strength ferrous sintered alloy excellent in wear resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a lightweight ferrous sintered alloy having a high strength, excellent in wear resistance and used as a material for various machine parts such as automotive parts and compressor parts and to provide a method for producing the same. SOLUTION: This high strength ferrous sintered alloy excellent in wear resistance has a compsn. contg., by weight, 1 to 5% Ni, 0.5 to 4% Mo, 0.3 to 3% Si and 0.3 to 1% C, furthermore contg., at need, 1 to 3% Cu, and the balance Fe with inevitable impurities, has 6.8 to 7.4g/cc density, and in which SiC is dispersed into the structure, preferably, by 0.03 to 0.3% as the ratio occupied in the whole body of the compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight, high tensile strength (hereinafter simply referred to as "high strength") used as a material for various mechanical parts such as automobile parts and compressor parts, and excellent wear resistance. The present invention relates to an iron-based sintered alloy and a method for producing the same.

[0002]

2. Description of the Related Art As a prior art, an iron-based sintered alloy is generally used as a material for various mechanical parts such as an automobile part and a compressor part. A method using an alloy steel powder is known, but C: described in JP-A-5-287452:
0.1% by weight or less, Mn: 0.08% by weight or less, Cr:
0.5-3% by weight, Mo: 0.1-2% by weight, S: 0.
01% by weight or less, P: 0.01% by weight or less, O: 0.2
% Or less, and further contains one or two of Ni: 0.2 to 2.5% by weight and Cu: 0.5 to 2.5% by weight, with the balance being Fe and unavoidable impurities. A material containing components such as Cr and Mo, such as an iron-based sintered alloy having a specific composition, is known as a high-strength material.

[0003]

However, in recent years, iron-based sintered alloy materials capable of accurately and mass-producing complicated-shaped parts with high precision have been widely used as materials for various mechanical parts such as automobile parts and compressor parts. In order to improve the performance of parts and to apply to parts where iron-based sintered materials have been difficult to use in the past, iron-based sintered alloys are even lighter and have higher strength. At the same time, there is an increasing demand for improved wear resistance. However, in response to these requirements, in the iron-based sintered alloy described in the above-mentioned Japanese Patent Application Laid-Open No. 5-287452, it is possible to obtain a uniform structure by using alloy steel powder. There was difficulty in further improving the properties, and it was not possible to sufficiently respond to the above demand, which was a problem.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
From the above viewpoints, we conducted research to obtain iron-based sintered alloys that are lightweight, high-strength, and have excellent wear resistance as materials for various mechanical parts such as automobile parts and compressor parts. , Fe-Mo alloy powder, C
Powder, Ni powder, Cu powder, etc. are prepared, these selected raw material powders are mixed with SiC powder, molded, sintered, a part of SiC is decomposed during sintering, and Si And C as a solid solution, and the other part is
An iron-based sintered alloy having a structure that remains dispersed as C is
It has been found that a high-strength iron-based sintered alloy having the same strength as the conventional one and having excellent wear resistance is obtained.

The present invention has been made on the basis of the above findings. (1) Ni: 1 to 5% and Mo: 0.5 to 4% by weight.
%, Si: 0.3-3%, C: 0.3-1%,
A high-strength iron-based sintered alloy having a composition consisting of Fe and inevitable impurities, a density of 6.8 to 7.4 g / cc, and SiC dispersed in the structure and having excellent wear resistance. (2) Ni: 1 to 5%, Mo: 0.5 to 4 by weight%
%, Si: 0.3-3%, C: 0.3-1%,
Further, it has a composition containing Cu: 1 to 3%, the balance being Fe and unavoidable impurities, and a density of 6.8 to 7.4 g /
A high-strength iron-based sintered alloy with excellent wear resistance in which SiC is dispersed in the structure. (3) The iron-based sintered alloy has excellent wear resistance according to (1) or (2), wherein SiC is dispersed in the structure by 0.03 to 0.3% by weight based on the entire composition. High strength iron-based sintered alloy. (4) Ni powder, SiC powder, C powder,
Using a powder selected from Cu powder and Fe-Mo powder, mixing and molding the powder, sintering,
A part of C is dissolved in the base material as Si and C, and the other part is dispersed and remains in the base material as SiC (1), (2)
Alternatively, the method for producing a high-strength iron-based sintered alloy excellent in wear resistance according to any one of (3). It is characterized by the following.

[0006] The high-strength iron-based sintered alloy according to the present invention comprises, as raw materials, Fe-Mo alloy powder, SiC powder, C powder, Ni powder.
A powder and a Cu powder are prepared, and these raw material powders are mixed, molded and sintered. The high-strength iron-based sintered alloy of the present invention uses SiC powder as a raw material, so that a part of SiC is decomposed during sintering and is dissolved in the base material as Si and C, and the other part is hardened. By dispersing and remaining in the substrate as SiC of
It was possible to improve the wear resistance while maintaining the conventional high strength.

[0007]

Embodiments of the present invention will be described below. The high-strength iron-based sintered alloy of the present invention is obtained by first using Fe-Mo alloy powder, SiC powder, Ni
Powder, C powder, and Cu powder are prepared, and these raw material powders are mixed with zinc stearate powder or ethylenebisstearamide, which is a lubricant at the time of molding, and compacted by pressing. Molding density is 6.8-7.4 g / cc
Is preferred. The green compact is sintered in a reducing atmosphere such as a mixed atmosphere of nitrogen and hydrogen in a temperature range of 1100 to 1150 ° C.

When sintered at this temperature, SiC added as a raw material partially decomposes into Si and C. Si usually hinders sintering due to its easy oxidizability and is difficult to alloy during sintering. However, in the present invention, since it is reduced by C in the vicinity of Si, diffusion into the substrate and alloying are difficult. It will be easier. Amount of decomposed SiC and residual SiC dispersed in the substrate
By adjusting the amount of, the high-strength iron-based sintered alloy of the present invention, martensite, bainite, pearlite, ferrite, austenite, a mixed structure of all or a part of SiC, while maintaining high strength, It becomes a sintered body that has both excellent wear resistance. If the product requires more strength, the sintered body may be subjected to heat treatment of quenching and tempering.

Next, the reason why the component composition of the high-strength iron-based sintered alloy of the present invention is limited as described above will be described.

(A) Ni Ni is effective in improving the strength and toughness, but its effect is not sufficient if its content is less than 1% by weight, while its effect is exceeded even if its content exceeds 5% by weight. Less is. Therefore,
The content was set to 1 to 5% by weight. A more preferred range for this content is 1.5-4.5% by weight.

(B) Mo Mo has the effect of improving the strength, but if the content is less than 0.5% by weight, the effect of improving the strength cannot be obtained, while the content of Mo exceeds 4% by weight. Then, the toughness is reduced, so the content is set to 0.5 to 4% by weight. A more preferred range for this content is 0.8-2.0% by weight.

(C) Si Si has an effect on hardening of ferrite and martensite, but if its content is less than 0.3% by weight, there is no effect of improving the hardness. On the other hand, if Si exceeds 3% by weight, If contained, the toughness is reduced, so the content is set to 0.3 to 3% by weight. A more preferred range of the Si content is 0.5.
~ 2% by weight.

(D) C C has the effect of improving the strength and hardness, but has no effect if its content is less than 0.3% by weight, while 1% by weight
If the content is more than 0.1%, the toughness is reduced. Therefore, the content is set to 0.3 to 1% by weight. A more preferable range of the content of C is 0.4 to 0.8% by weight.

(E) Cu Cu is added as necessary because it has the effect of improving the strength, expanding the sintered body, and adjusting the dimensions. If its content is less than 1% by weight, the effect is reduced. On the other hand, if it exceeds 3% by weight, the dimensional variation becomes large,
Since the toughness also decreases, the content of Cu is set to 1 to 3% by weight. A more preferred range for the Cu content is 1.5.
~ 2.5% by weight.

(F) SiC SiC has the effect of improving the wear resistance of the sintered body when dispersed in the base material of the sintered body, but if its content is less than 0.03% by weight. The effect is not so great. On the other hand, when the content exceeds 0.3% by weight, a decrease in strength starts to appear.
It was determined to be 0.3% by weight.

(G) Density The density acts to adjust the weight of the sintered body. If the value is less than 6.8 g / cc, the desired high strength of the sintered body cannot be obtained. However, if it exceeds 7.4 g / cc, the effect of reducing the weight of the sintered body will decrease, so the value is set to 6.8 to 7.4 g / cc.

[0017]

EXAMPLES Examples of the present invention will be specifically described below. As raw material powder, average particle size: Fe-
Mo powder, average particle size: 3 μm SiC powder, average particle size:
A 6 μm Ni powder, a C powder having an average particle diameter of 17 μm, and a Cu powder having an average particle diameter of 22 μm were prepared, and these raw material powders were mixed so as to have a compounding composition shown in Tables 1 and 2, and further a mold was prepared. A predetermined amount of a zinc stearate powder or ethylene bisstearamide as a lubricant at the time of molding is added and mixed, and the mixture is press-molded to 10 mm × 10 mm × 50 mm.
A molded article having the following dimensions was produced. This molded body is N ₂ −
Sintered in a mixed atmosphere of 20% H ₂ at a temperature of 1125 ° C. for 60 minutes, and having the component composition and density shown in Tables 3 and 4 and having excellent wear resistance according to the present invention. Bonding metals 1 to 15 (hereinafter simply referred to as sintered alloys 1 to 15 of the present invention) were produced. In addition, in order to produce a conventional sintered alloy, alloy steel powders having the compositions shown in Table 2 were prepared.
After adding and mixing 1% by weight, 10 mm is compression molded.
A molded body having dimensions of × 10 mm × 50 mm was produced. These compacts are placed in a mixed atmosphere of N ₂ -20% H ₂
Temperature: 1125 ° C, sintering for 60 minutes, and the conventional iron-based sintered alloys 1 to 3 having the component composition and density shown in Table 5 Was prepared.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

Abrasion test pieces were prepared by polishing the obtained sintered alloys 1 to 15 of the present invention and the conventional sintered alloys 1 to 3 respectively, and then a load of 3.2 k was applied to evaluate wear resistance.
g, distance: 200 m, speed: 0.78 m / s, partner material:
An Ogoshi type abrasion test was performed under the conditions of S45C and dry, respectively, and their specific abrasion amounts are shown in Table 6. Further, a tensile test piece having a parallel part: 4.5 mm in diameter was prepared by machining, and then a tensile test was performed at a tensile speed of 1.5 mm / min, and their tensile strengths are shown in Table 6.

[0024]

[Table 6]

[0025]

As is clear from Table 6, the sintered alloy 1 of the present invention
Comparing the conventional sintered alloys 1 to 3 with the conventional sintered alloys 1 to 3, it is understood that the sintered alloys 1 to 15 of the present invention are more excellent in wear resistance than the conventional sintered alloys 1 to 3. As described above, the sintered alloy of the present invention is lightweight, has high strength, and is excellent in wear resistance, so that it is used as a material for various mechanical parts such as automobile parts and compressor parts. It has excellent effects.

Claims (4)

[Claims] (1) Ni: 1 to 5% and Mo: 0.
5 to 4%, Si: 0.3 to 3%, C: 0.3 to 1%, with the balance being Fe and unavoidable impurities, having a density of 6.8 to 7.4 g / cc. A high-strength iron-based sintered alloy having excellent wear resistance, characterized in that SiC is dispersed in the structure. 2. Ni: 1 to 5% by weight, Mo: 0.1% by weight.
5 to 4%, Si: 0.3 to 3%, C: 0.3 to 1%, further contains Cu: 1 to 3%, the balance being Fe and inevitable impurities, Density 6.8-7.
A high-strength iron-based sintered alloy having a wear resistance of 4 g / cc, wherein SiC is dispersed in the structure. 3. The steel according to claim 1, wherein in the iron-based sintered alloy, SiC is dispersed in the structure in an amount of 0.03 to 0.3% by weight based on the total composition. High-strength iron-based sintered alloy with excellent wear properties. 4. Raw materials such as Ni powder, SiC powder, C
Using a powder selected from powder, Cu powder and Fe-Mo powder, mixing and molding, sintering, and dissolving a part of SiC as Si and C in the base material during sintering, The method for producing a high-strength iron-based sintered alloy having excellent wear resistance according to any one of claims 1, 2 and 3, wherein the other part is dispersed and remained in the substrate as SiC.