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Process for production of sintered compact by powder metallurgy

A technology of powder metallurgy and manufacturing method, which is applied in the field of manufacturing sintered bodies, and can solve the problems of reducing the strength of sintered bodies and the like

Active Publication Date: 2011-08-24
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Regarding the alloy steel powder of Patent Document 3, for example, if the Mn content is increased, the problem of strength is solved, but since Mn is an element that is easily oxidized, if a large amount of Mn is added, the sintering after press forming or the Oxide is formed by heat treatment, and the strength of the sintered body is reduced

Method used

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  • Process for production of sintered compact by powder metallurgy
  • Process for production of sintered compact by powder metallurgy
  • Process for production of sintered compact by powder metallurgy

Examples

Experimental program
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Effect test

Embodiment 1

[0081] Raw material powders obtained by adding and mixing graphite powder in an amount such that the amount of C after sintering (the amount of C in the sintered compact) was 0.3% by mass to alloy steel powders having the compositions shown in Table 1 were used. The raw material powder was molded into a rectangular parallelepiped molded body with a bottom surface of 10 mm×60 mm under a molding pressure of 700 MPa, and sintered at 1200° C. in a nitrogen atmosphere. After carburizing, quenching and tempering the cuboidal sintered body, the tensile strength and impact value were measured, and the metal structure was observed. In addition, C analysis was performed on the sintered body before carburizing, quenching and tempering. These results are shown in Table 1 together.

[0082] In Table 1, the sample number 1 (comparative example) in which the amount of Cr in the alloy steel powder is small has a low tensile strength of the sintered body due to the small amount of martensite ...

Embodiment 2

[0090] The alloy steel powder (Cr: 0.3% by mass, Mn: 0.3% by mass, Mo: 0.2% by mass, C: 0.004% by mass, O: 0.3% by mass) used in Sample No. 2 of Example 1 (Table 1) was used , the balance being Fe and unavoidable impurities), graphite powder and molding lubricant (zinc stearate) are added and mixed in such an amount that the amount of C after sintering (the amount of C in the sintered body) becomes 0.3% by mass raw powder. This raw material powder was molded into a cuboid molded body with a bottom surface of 10 mm×60 mm, and sintered in a nitrogen atmosphere. After carburizing, quenching and tempering this rectangular parallelepiped sintered body, the tensile strength and density were measured. The results are shown in Table 2 together with the molding pressure and sintering temperature. also, figure 1 The comparison between the relationship between the forming pressure and tensile strength of Sample Nos. 2, 5 to 7 and the relationship between the forming pressure and tensi...

Embodiment 3

[0096] A raw material powder obtained by adding and mixing graphite powder to alloy steel powder having the composition shown in Table 3 was used. The raw material powder was molded into a rectangular parallelepiped molded body with a bottom surface of 10 mm×60 mm under a molding pressure of 700 MPa, and sintered at 1200° C. in a nitrogen atmosphere. The tensile strength of this rectangular parallelepiped sintered body was measured, and C analysis was performed simultaneously. These results are shown in Table 3 together.

[0097] In Table 3, since the addition amount of graphite powder was fixed at 0.60 mass % for sample numbers 1 to 4, the amount of decarburization increased while the amount of oxygen in the alloy steel powder increased, and the amount of C in the sintered body varied. Thus, the tensile strength varies greatly. On the other hand, in Sample Nos. 5 to 7, since graphite powder was added in consideration of the amount reacted with oxygen during sintering, there...

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Abstract

A process for production of a sintered compact by powder metallurgy, by which a high-strength sintered compact can be produced at a low cost in spite of using an Ni- or Cu-free alloy steel powder for powder metallurgy. The process comprises using an alloy steel powder for powder metallurgy which contains Cr: 0.3 to 0.7mass%, Mn: 0.1 to 0.5mass%, Mo: 0.1 to 0.5mass%, and O: 0.25 to 0.5mass% with the balance being Fe and unavoidable impurities, compacting the alloy steel powder or a mixed powder containing the same at a pressure of 700MPa or higher, and then sintering the obtained compact at a temperature of 1150 to 1300 DEG C.

Description

technical field [0001] The present invention relates to a method for producing a sintered body suitable for high-strength sintered parts for automobiles and the like using powder metallurgy. Background technique [0002] Powder metallurgy, in which iron powder or alloy steel powder is press-formed in a mold and then sintered to obtain a sintered body, is widely used in the manufacture of automotive parts such as gears that require high dimensional accuracy. A sintered body used as an automotive part usually has about 6.0g / cm 3 ~ about 7.1g / cm 3 density, which is produced by filling a mixed powder mixed with Cu powder, graphite powder, lubricant, etc. [0003] In automobile parts, when manufacturing parts requiring high strength (hereinafter referred to as high-strength sintered parts for automobiles), alloying elements (such as: Ni, Cu, Mo, Cr, Mn, etc.) are added to iron-based powders as The technology used for raw material powder has been put into practical use. The st...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C33/02C22C38/00
CPCC22C38/002C22C38/004B22F2998/10C22C38/04C22C33/0264C22C38/22C22C38/00B22F3/02B22F3/10
Inventor 宇波繁尾崎由纪子筒井唯之山西祐司
Owner JFE STEEL CORP
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