Production method for sintered machine components

Abstract

A production method for sintered machine components, includes preparing an Fe alloy powder A, an Fe alloy powder B, an Fe—P powder, and a graphite powder. The Fe alloy powder A consists of, by mass %, 25 to 45% of Cr, 1.0 to 3.0% of Mo, 1.0 to 3.0% of Si, 0.5 to 1.5% of C, and the balance of Fe and inevitable impurities. The Fe alloy powder B consists of, by mass 15 to 35% of Cr, 15 to 30% of Ni, and the balance of Fe and inevitable impurities, and the Fe—P powder consists of 10 to 30 mass % of P and the balance of Fe and inevitable impurities. The production method further includes mixing 40 to 60 mass % of the Fe alloy powder B, 1.0 to 5.0 mass % of the Fe—P powder, and 0.5 to 3.5 mass % of the graphite powder with the Fe alloy powder A into a mixed powder. The production method further includes compacting the mixed powder into a green compact and sintering the green compact.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to a production method for sintered machine components; the production method may be preferably used for, for example, turbo components of turbochargers, and specifically, nozzle bodies that must have heat resistance, corrosion resistance, and wear resistance.

[0003] 2. Background Art

[0004] In general, in a turbocharger fixed to an internal combustion engine, a turbine is rotatably supported by a turbine housing connected to an exhaust manifold of the internal combustion engine, and plural nozzle vanes are rotatably supported such that the nozzle vanes surround the outer circumference of the turbine. Exhaust gas flowing in the turbine housing flows from the outer circumference of the turbine into the turbine and is discharged in the axial direction, thereby rotating the turbine. A compressor is provided at the same shaft as the shaft of the turbine and is at a side opposite to the side with the nozzl...

Examples

first example

[0026]Hereinafter, practical examples of the present invention are described in detail. In the following description, each of the “%” symbols represents “mass %”. An Fe alloy powder A (Fe alloy powder disclosed in Japanese Patent No. 3784003), an Fe alloy powder B, an Fe-20P alloy powder, and a graphite powder were prepared. The Fe alloy powder A consisted of 30% of Cr, 2% of Mo, 2% of Si, and 1% of C, the Fe alloy powder B consisted of 25% of Cr, 20% of Ni, and the balance of Fe and inevitable impurities, and the Fe-20P powder included 20% of P. An amount from 30 to 70% of the Fe alloy powder B was added to the Fe alloy powder A, and 2.5% of the Fe-20P powder and 2.7% of the graphite powder were added thereto, whereby a mixed powder was obtained. The mixed powder was compacted at a compacting pressure of 600 MPa into a pillar shape having an outer diameter of 10 mm and a height of 10 mm, whereby a green compact was obtained. The green compact was sintered at 1200° C. for 60 minutes...

second example

[0029]Fe alloy powder B having a composition shown in Table 2 was prepared. Then, 50% of the Fe alloy powder B, 2.5% of the Fe-20P powder, and 2.7% of the graphite powder were added to the Fe alloy powder A in the first example, and they were mixed together into a mixed powder. The mixed powder was compacted and was sintered in the same manner as in the first example, whereby samples Nos. 8 to 18 were formed. In these samples, increases in the weights due to oxidation, tensile strength (high-temperature strength), and thermal expansion coefficient were measured in the same manner as in the first example. These results and the results of the sample No. 3 in the first example are shown in Table 2.

TABLE 2OxidizedHigh-amounttemperatureThermalSam-Mixing ratio mass %(Air × 100 hr)strengthexpansionpleFe alloyFe alloy powder BFe—20PGraphiteg / m2(800° C.)coefficientNo.powder AFeCrNipowderpowder700800900MPa10−6 K−1Notes8Balance50.0Balance10.020.02.52.711265227016.4Exceedslower limit ofCr amoun...

third example

[0032]Next, 50% of the Fe alloy powder B in the first example, the Fe-20P powder, and the graphite powder were added to the Fe alloy powder A in the first example, and they were mixed together into a mixed powder. The amounts of the Fe-20P powder and the graphite powder were varied as shown in Table 3. The mixed powder was compacted and was sintered in the same manner as in the first example, whereby samples Nos. 19 to 31 were formed. In these samples, increases in the weights due to oxidation, tensile strength (high-temperature strength), and thermal expansion coefficient were measured in the same manner as in the first example. These results and the results of the sample No. 3 in the first example are shown in Table 3.

TABLE 3OxidizedHigh-Mixing ratio mass %amounttemperatureThermalFe alloyFe alloy(Air × 100 hr)strengthexpansionSamplepowder Apowder BFe—20PGraphiteg / m2(800° C.)coefficientNo.(Fe—30Cr—2Mo—2Si—1C)(Fe—25Cr—20Ni)powderpowder700800900MPa10−6 K−1Notes19Balance50.02.50.31351...

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to a production method for sintered machine components; the production method may be preferably used for, for example, turbo components of turbochargers, and specifically, nozzle bodies that must have heat resistance, corrosion resistance, and wear resistance.

[0003] 2. Background Art

[0004] In general, in a turbocharger fixed to an internal combustion engine, a turbine is rotatably supported by a turbine housing connected to an exhaust manifold of the internal combustion engine, and plural nozzle vanes are rotatably supported such that the nozzle vanes surround the outer circumference of the turbine. Exhaust gas flowing in the turbine housing flows from the outer circumference of the turbine into the turbine and is discharged in the axial direction, thereby rotating the turbine. A compressor is provided at the same shaft as the shaft of the turbine and is at a side opposite to the side with the nozzl...

Examples

first example

[0026]Hereinafter, practical examples of the present invention are described in detail. In the following description, each of the “%” symbols represents “mass %”. An Fe alloy powder A (Fe alloy powder disclosed in Japanese Patent No. 3784003), an Fe alloy powder B, an Fe-20P alloy powder, and a graphite powder were prepared. The Fe alloy powder A consisted of 30% of Cr, 2% of Mo, 2% of Si, and 1% of C, the Fe alloy powder B consisted of 25% of Cr, 20% of Ni, and the balance of Fe and inevitable impurities, and the Fe-20P powder included 20% of P. An amount from 30 to 70% of the Fe alloy powder B was added to the Fe alloy powder A, and 2.5% of the Fe-20P powder and 2.7% of the graphite powder were added thereto, whereby a mixed powder was obtained. The mixed powder was compacted at a compacting pressure of 600 MPa into a pillar shape having an outer diameter of 10 mm and a height of 10 mm, whereby a green compact was obtained. The green compact was sintered at 1200° C. for 60 minutes...

second example

[0029]Fe alloy powder B having a composition shown in Table 2 was prepared. Then, 50% of the Fe alloy powder B, 2.5% of the Fe-20P powder, and 2.7% of the graphite powder were added to the Fe alloy powder A in the first example, and they were mixed together into a mixed powder. The mixed powder was compacted and was sintered in the same manner as in the first example, whereby samples Nos. 8 to 18 were formed. In these samples, increases in the weights due to oxidation, tensile strength (high-temperature strength), and thermal expansion coefficient were measured in the same manner as in the first example. These results and the results of the sample No. 3 in the first example are shown in Table 2.

TABLE 2OxidizedHigh-amounttemperatureThermalSam-Mixing ratio mass %(Air × 100 hr)strengthexpansionpleFe alloyFe alloy powder BFe—20PGraphiteg / m2(800° C.)coefficientNo.powder AFeCrNipowderpowder700800900MPa10−6 K−1Notes8Balance50.0Balance10.020.02.52.711265227016.4Exceedslower limit ofCr amoun...

third example

[0032]Next, 50% of the Fe alloy powder B in the first example, the Fe-20P powder, and the graphite powder were added to the Fe alloy powder A in the first example, and they were mixed together into a mixed powder. The amounts of the Fe-20P powder and the graphite powder were varied as shown in Table 3. The mixed powder was compacted and was sintered in the same manner as in the first example, whereby samples Nos. 19 to 31 were formed. In these samples, increases in the weights due to oxidation, tensile strength (high-temperature strength), and thermal expansion coefficient were measured in the same manner as in the first example. These results and the results of the sample No. 3 in the first example are shown in Table 3.

TABLE 3OxidizedHigh-Mixing ratio mass %amounttemperatureThermalFe alloyFe alloy(Air × 100 hr)strengthexpansionSamplepowder Apowder BFe—20PGraphiteg / m2(800° C.)coefficientNo.(Fe—30Cr—2Mo—2Si—1C)(Fe—25Cr—20Ni)powderpowder700800900MPa10−6 K−1Notes19Balance50.02.50.31351...

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