JP2017137533A - Composite sintered compact and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently enhance bonding strength of a composite sintered compact without increasing production cost.SOLUTION: A method for producing a composite sintered compact comprises: a powder compacting step of compressing raw material powders mainly composed of iron to mold a first green compact and a second green compact; and a sintering step of heating the first green compact and the second green compact while bringing them into pressure contact with each other, thereby obtaining a first sintered compact and a second sintered compact and diffusion-bonding the first sintered compact and the second sintered compact. The raw material powder of the first green compact contains phosphorus. The heating temperature in the sintering step is 1,050°C or higher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a composite sintered body formed by diffusion bonding a plurality of sintered bodies and a method for producing the same.

  A sintered compact, which is a kind of powder metallurgy product, is manufactured through a compacting process in which a powder mixture containing metal powder is compressed to form a compact and a sintering process in which the compact is heated at a predetermined temperature. Is done. Since the compacting process is often performed using a uniaxial press, if the compact has an undercut shape, the compact cannot be removed from the mold. For this reason, the shape of the product has been limited.

  For example, in the case of a composite sintered body obtained by joining a plurality of sintered bodies, a product having a complicated shape having an undercut shape can be manufactured. In manufacturing such a composite sintered body, as a method of joining a plurality of sintered bodies, the joining surfaces are diffusion-bonded by heating in a state where sufficient pressure is applied to the joining surfaces of the plurality of green compacts. Sintering diffusion bonding techniques are known.

  In order to increase the bonding force by the sintered diffusion bonding, it is only necessary to increase the fitting stress by increasing the tightening margin of the fitting portions of the plurality of green compacts. However, since the green compact is very brittle due to the property of being an aggregate of powder, there is a risk that it will be damaged if excessively tightened.

  For example, Patent Document 1 shown below discloses a method for manufacturing a composite sintered machine part in which an inner member made of an iron-based sintered body and an outer member made of an iron-based green compact are fitted and heated. ing. In this manufacturing method, the raw material powder of the outer member has a composition such that the amount of thermal expansion in a high temperature region of 750 ° C. or higher is smaller than that of the inner member. Thus, by making the amount of thermal expansion of the outer member smaller than the amount of thermal expansion of the inner member, the fitting stress of both members is increased, and the joint strength of both members is increased.

Japanese Patent No. 3954235

  However, in order to sufficiently increase the joint strength between the two members, it is necessary to greatly vary the thermal expansion amounts of the two members, so that the materials used are greatly limited. Actually, since it is necessary to select materials for both members so as to satisfy various required characteristics, it is difficult to increase the difference in thermal expansion between the materials of both members as described above. Therefore, it is difficult to sufficiently increase the joint strength between both members due to the difference in thermal expansion.

  Also, the porosity of the green compact surface is usually higher than the internal porosity. This is because the powder and the mold are in contact with each other during compression molding. In other words, since the green compact is molded by applying pressure to the powder filled in the mold, a large friction occurs between the powders and between the powder and the mold, and particularly the friction between the powder and the mold is very high. growing. For example, adding a solid lubricant to the powder may reduce the frictional force, but it is often not sufficient. As a result, the amount of movement of the powder in contact with the mold becomes smaller than the amount of movement of the internal powder, and the number of pores on the surface of the green compact becomes larger than that inside. In this case, the contact area between the green compact and other members (for example, other green compacts) is reduced, and the bonding strength of the composite sintered body may be insufficient.

  For example, the porosity of the green compact surface can be reduced by increasing the compression ratio of the green compact to increase the density or smoothing the surface of the green compact during compression molding. However, since there is a limit to increasing the density of the green compact, it is difficult to sufficiently increase the joint strength of the composite sintered body. Further, if a step of leveling the surface of the green compact is added, the manufacturing cost increases due to an increase in the number of steps.

  As described above, the technical problem to be solved by the present invention is to sufficiently increase the bonding strength of the composite sintered body without incurring high manufacturing costs.

  By the way, when manufacturing a sintered compact, phosphorus may be mix | blended with raw material powder. Phosphorus has an effect of promoting sintering. Therefore, by blending phosphorus, sintering proceeds sufficiently even at a relatively low temperature, and a sintered body having a desired strength can be obtained. Since the sintering temperature greatly affects the manufacturing cost, the manufacturing cost can be significantly reduced by lowering the sintering temperature by adding phosphorus. As described above, the main purpose of blending phosphorus into the raw material powder of the sintered body is to reduce the manufacturing cost by lowering the sintering temperature.

  As a result of the study by the present inventors, in producing a composite sintered body by heating a green compact mainly composed of iron in a state of being pressed against another member (for example, another green compact), It became clear that the bonding strength of the composite sintered body can be increased by adding phosphorus to the raw material powder and heating it at a relatively high temperature (for example, 1050 ° C. or higher). This is because the phosphorus alloy (for example, iron-phosphorus alloy) melts, which causes liquid phase sintering, and in particular, the pores of the sintered body, particularly between the sintered body and other members (for example, other sintered bodies). It is thought that the contact area between the sintered body and the other member increased due to the progress of the sintering while filling a large number of pores existing at the boundary, and the joining interface was strengthened.

  Based on the above findings, the present invention provides a compacting step of forming a first green compact and a second green compact by compressing a raw material powder containing iron as a main component, the first green compact, By heating the second green compact while being pressed against each other, the first sintered body and the second sintered body are obtained, and the first sintered body and the second sintered body are diffusion bonded. A method of manufacturing a composite sintered body including a sintering step, wherein the raw material powder of the first green compact contains phosphorus, and a heating temperature (sintering temperature) in the sintering step is 1050 ° C. or higher. A method for producing a sintered body is provided.

  The present invention is not limited to the case where the green compacts are pressed and heated, but can also be applied to the case where the green compact and other members (for example, a sintered body or a melted material) are pressed and heated. That is, the present invention comprises a compacting process in which a raw material powder containing iron as a main component is compressed to form a green compact, and the green compact and another member are heated in a state of being pressed against each other, thereby sintering. And a sintering process for diffusion bonding the sintered body and the other member, wherein the green compact raw material powder contains phosphorus, and the sintered body is sintered. Provided is a method for producing a composite sintered body in which the heating temperature (sintering temperature) in the process is 1050 ° C. or higher.

Further, as described above, by heating the green compact containing phosphorus at a relatively high temperature, sintering of the sintered body proceeds excessively, and the number of pores decreases due to crystal grain growth, for example, per unit area. The number of holes is 5000 / mm ² or less. Accordingly, the present invention is a composite sintered body having a first member made of a sintered body containing iron as a main component and a second member diffusion-bonded to the sintered body, wherein the sintered body is , And can be characterized as a composite sintered body containing phosphorus and having 5,000 holes / mm ² or less per unit area. The second member can be composed of, for example, another sintered body containing iron as a main component. Other sintered bodies may have the same composition as the sintered body of the first member.

  If the phosphorus content in the sintered body is too small, the bonding strength cannot be sufficiently increased. On the other hand, if the content of phosphorus in the sintered body is too large, the segregation of phosphorus to the crystal grain boundaries of the sintered body becomes significant and the impact value decreases. Accordingly, the phosphorus content in the sintered body, that is, the phosphorus content in the raw material powder of the green compact is preferably set within a predetermined range, specifically 0.2 mass% or more and 1.0 mass%. The following is preferable.

If the sintering proceeds too much, the crystal grains and internal vacancies become too large, which may lead to a decrease in strength of the composite sintered body. For this reason, it is preferable that a sintering temperature shall be 1200 degrees C or less. The number of pores per unit area of the sintered body is preferably 1000 / mm ² or more.

  By the way, since the density of the sintered body increases with the progress of the sintering, the degree of progress of the sintering can usually be determined by the density of the sintered body. However, if the sintering proceeds to some extent, the density of the sintered body hardly changes even if the sintering proceeds further. Thereafter, the internal vacancies of the sintered body coalesce or the internal vacancies become spherical. Or changes in the size, distribution, shape, etc. of the internal holes. Therefore, when the progress of the sintering is determined further before the density has changed, it can be determined from the shape of the internal pores of the sintered body.

Specifically, if the arithmetic average value of the circularity of the pores of 80 μm ² or more among the internal pores of the sintered body is larger than 0.2, it can be determined that the sintering is sufficiently advanced. On the other hand, if the sintering progresses too much, the crystal grains become too large and the joint strength between the two sintered bodies may be reduced. Therefore, the arithmetic average value of the circularity of the pores is less than 0.5. Preferably there is. The circularity is a value obtained by dividing the hole area S by the square of the peripheral length L and multiplying by 4π (circularity = 4π · S / L ² ).

Alternatively, if the arithmetic average value of the acicular ratio of the pores of 80 μm ² or more among the internal pores of the sintered body is less than 1.9, it can be determined that the sintering is sufficiently advanced. On the other hand, if the sintering proceeds too much, the crystal grains become too large, which may lead to a decrease in the bonding strength of both sintered bodies. Therefore, the arithmetic average value of the needle-like ratio of the holes is from 1.5. Larger is preferred. The acicular ratio is a value obtained by dividing the absolute maximum length of a hole by a diagonal width (the shortest distance between two straight lines parallel to the absolute maximum length sandwiching the hole) (see FIG. 3).

  As described above, phosphor is added to a green compact containing iron as a main component, and then heated at a relatively high temperature so that sintering proceeds excessively. The bonding strength between the bonded body and the other member can be increased.

It is sectional drawing of the composite sintered compact which concerns on one Embodiment of this invention. The left figure is a cross-sectional photograph of a composite sintered body that does not contain phosphorus (comparative product), and the right figure is a cross-sectional photograph of a composite sintered body that contains phosphorus (product of the present invention). It is a figure which shows the image of acicular ratio.

  FIG. 1 shows a composite sintered body according to an embodiment of the present invention. This composite sintered body includes a first member 1 and a second member 2. The first member 1 in the illustrated example is a gear having a tooth surface on the outer periphery, for example, and the second member 2 is a boss having a shaft portion, for example. A shaft portion provided in the second member 2 is press-fitted into the inner periphery of the first member 1, and the inner peripheral surface of the first member 1 and the outer peripheral surface of the shaft portion of the second member 2 are diffusion bonded.

  The 1st member 1 consists of a sintered compact which has iron as a main component. The second member 2 is made of, for example, a sintered body. In the present embodiment, the second member 2 is made of a sintered body having iron as a main component, particularly a sintered body having the same composition as the sintered body of the first member 1. In addition, you may comprise the 2nd member 2 by the member which consists of a sintered compact of the composition different from the sintered compact of the 1st member 1 other than the above, or a melting material.

  The composite sintered body includes a mixing step in which various powders are mixed to produce a raw material powder, a compacting step in which the raw material powder is compressed to form a green compact, and the green compact is made up of other members (other members in this embodiment). And a sintering process in which a composite sintered body is obtained by heating in a state of pressure contact with the green compact).

  As the raw material powder, an iron-based powder containing iron as a main component is used to ensure the strength of machine parts. Specifically, the iron powder is 93.0% by mass or more (preferably 95.0% by mass or more). An iron-based powder containing is used. This iron-based powder contains phosphorus (for example, phosphorus alloy powder). The iron-based powder of the present embodiment includes iron powder, phosphorus alloy powder, copper powder, and graphite powder.

  As the iron powder, known powders such as reduced iron powder and water atomized iron powder can be widely used. Use reduced iron powder with regular shape. As the iron powder, alloy steel powder alloyed with a hardenability improving element or the like can also be used.

As the phosphorus alloy powder, for example, an iron-phosphorus compound, specifically, an alloy powder containing Fe ₃ P is used. Phosphorus has a function of promoting sintering, but if the amount of phosphorus is too small, the effect cannot be sufficiently obtained. If the amount of phosphorus is too large, segregation of phosphorus to crystal grain boundaries becomes remarkable and the impact value decreases. . For this reason, the ratio of the phosphorus alloy powder in the raw material powder is set so that phosphorus is within a predetermined range with respect to the raw material powder. Specifically, the ratio of phosphorus to the raw material powder is 0.2% by mass or more, preferably 0.3% by mass or more, and more preferably 0.5% by mass or more. The ratio of phosphorus to the raw material powder is 1.0% by mass or less, preferably 0.8% by mass or less, and more preferably 0.6% by mass or less.

  Copper powder is mix | blended in the ratio of 1.0 mass%-5.0 mass% with respect to raw material powder. If the ratio of the copper powder is too small, the strength of the sintered body is reduced, and if it is too large, the diffusion of carbon is inhibited and the strength and hardness of the sintered body are reduced. As the copper powder, electrolytic copper powder or atomized copper powder can be used. If electrolytic copper powder having a dendritic shape as a whole particle is used, it is more preferable because the strength of the compact can be increased and the copper particles can easily diffuse into the iron particles during sintering.

  Graphite powder functions as an internal lubricant that reduces friction between powders during compression molding and reacts with iron and carbon during sintering to form a hard pearlite phase. If the graphite powder is too small, compression molding becomes difficult and the strength of the sintered body cannot be ensured. On the other hand, when there is too much graphite powder, iron will become a cementite structure | tissue, it becomes weak and causes a strength fall. For this reason, the compounding ratio of the graphite powder in the raw material powder is 0.2 mass% to 1.0 mass%. As the graphite powder, scaly artificial graphite powder is preferably used.

A raw material powder is produced by adding various molding aids, for example, a lubricant for improving releasability, to the powders described above and mixing them (mixing step). The blending ratio of each powder at this time is phosphorus (phosphorus component in iron-phosphorus alloy powder): 0.2% by mass to 1.0% by mass, copper powder: 1.0% by mass to 5.0% as described above. % By mass, graphite powder: 0.2% by mass to 1.0% by mass, other: 0% by mass to 1.0% by mass, the balance being iron (iron powder and iron component in iron-phosphorus alloy powder) . By supplying this raw material powder to the mold of the molding machine and compressing it, the first green compact and the second green compact having substantially the same shape as the first member 1 and the second member 2 are formed (green compact). Process). In this embodiment, the compacting process is performed at room temperature. Moreover, compression molding conditions are set so that the density of the sintered compact which comprises the 1st member 1 and the 2nd member 2 will be 6.6-7.0 g / cm < ³ >.

  Thereafter, the shaft portion of the second green compact is press-fitted into the inner periphery of the first green compact, and these are fitted and integrated with a tightening margin. And by heating this integral product, while forming the 1st member 1 and the 2nd member 2 which consist of a sintered compact, these are utilized using the spreading | diffusion of the atom produced between the joining surfaces of both the members 1 and 2. Join (sinter diffusion bonding).

FIG. 2 is a cross-sectional photograph showing a comparison between a composite sintered body not containing phosphorus (left figure) and a composite sintered body containing phosphorus (right figure). Specifically, the composite sintered body in the left figure contains 3.0% by mass of copper and 0.9% by mass of graphite, and the balance is iron. The composite sintered body in the right figure contains copper. It contains 3.0% by mass, 0.9% by mass of graphite, 0.6% by mass of phosphorus, and the balance being iron. The sintering temperature is 1200 ° C. for all. In the composite sintered body in the left figure, which does not contain phosphorus, fine pores are dispersed (that is, crystal grains are relatively small), and the joint surface of the sintered bodies indicated by the XX line shows a cross-sectional structure. It remains to the extent that it can be confirmed. Specifically, the number of pores per unit area of this composite sintered body exceeds 5000 / mm ² . On the other hand, in the composite sintered body of the right figure containing phosphorus, relatively coarse pores are dispersed (that is, the crystal grains are relatively coarse), and the joint surface between the sintered bodies indicated by the Y-Y line is: It disappears to the extent that it cannot be confirmed from the cross-sectional structure. This is because the green compact containing phosphorus is heated at a relatively high temperature, and the phosphor alloy powder (for example, Fe ₃ P) is melted to cause liquid phase sintering, and sintering while filling a large number of surface vacancies. This is thought to be because of progress. Specifically, the number of pores per unit area of the composite sintered body is 1000 / mm ² or more and 5000 / mm ² or less.

When the sintering temperature is lower than 1050 ° C., Fe ₃ P in the raw material powder does not dissolve, so liquid crystal sintering does not occur, and the bonding interface between the sintered bodies cannot be strengthened. In addition, when the sintering temperature is 1050 ° C. to 1150 ° C., liquid phase sintering with Fe ₃ P occurs, but since the progress of the sintering is slow, the pores present at the bonding interface between the sintered bodies are sufficiently lost. do not do. For this reason, sintering temperature shall be 1050 degreeC or more, Preferably it shall be 1150 degreeC or more. In the present embodiment, since the copper is melted and diffused on the iron surface, the sintering temperature is set to be equal to or higher than the melting point of copper (1083 ° C.). On the other hand, when the sintering temperature exceeds 1200 ° C., the voids at the bonding interface between the sintered bodies are almost disappeared by the liquid phase sintering of Fe ₃ P, but the sintering proceeds excessively. Internal vacancies and crystal grains become coarse, leading to a decrease in strength. For this reason, it is preferable that a sintering temperature shall be 1200 degrees C or less.

  The sintering temperature of the iron-based sintered body containing phosphorus is generally set to a relatively low temperature (1000 ° C. or lower) in order to reduce costs. However, in the present invention, the sintering temperature of the iron-based green compact containing phosphorus is set to the same level as the sintering temperature of a normal iron-based sintered body not containing phosphorus. Thereby, the joining strength between the sintered bodies is improved without requiring a separate process such as leveling the surface of the green compact, and the overall strength of the composite sintered body is increased. By sintering, copper and carbon (graphite) dissolve in iron and the lubricant disappears.

  In the above description, the case where heating is performed in a state where the first powder compact and the second powder compact are combined is exemplified, but the method for manufacturing the composite sintered compact is not limited to this. For example, you may heat the compact obtained by said procedure in the state mutually press-contacted with the other member which consists of a sintered compact or melted material previously manufactured at another process. As a result, the sintered body obtained by sintering the green compact and the other member are diffusion bonded to form a composite sintered body.

  In order to confirm the effect of the present invention, the following experiment was conducted.

In this experiment, the materials shown in Table 1 below were used. As the raw material powder, iron-phosphorus alloy powder containing Fe ₃ P equivalent to 0.6% by mass of phosphorus, 3.0% by mass of copper powder, 0.9% by mass of graphite, 1.0% by mass of A lubricant was included, and the remainder was iron powder. The raw material powder obtained by mixing each powder is compressed into a cylindrical green compact with an outer diameter of 23.2 mm, an inner diameter of 16.4 mm and a thickness of 7 mm, and a cylindrical green compact with a diameter of φ16.4 mm and a thickness of 9 mm. Molded. The compression molding conditions were controlled so that the sintered density was 6.75 to 6.85 g / cm ³ at room temperature. After molding, a cylindrical green compact was pressed into a cylindrical green compact to produce a composite green compact. The clamping allowance for both compacts was 40 μm. This composite green compact was heated to produce a composite sintered body.

  For evaluating the composite sintered body, the crushing strength and bonding strength were measured. The crushing strength was measured in accordance with JIS Z 2507 using a cylindrical sintered body obtained by heating only a cylindrical green compact. Bonding strength is the state in which one end surface of the cylindrical sintered body in the axial direction is supported by a jig, the cylindrical sintered body is pushed in from the other axial direction, a load is applied, and the composite sintered body is broken at the joint surface. I let you. The bonding strength was a value obtained by dividing the maximum load at the time of rupture by the side area of the bonding surface of both sintered bodies.

Moreover, in order to confirm the progress of the sintering of the composite sintered body, the number of pores per unit area was measured using commercially available image analysis software (for example, WinROOF manufactured by Mitani Corporation). Specifically, a predetermined observation range (for example, an area of 0.6 × 0.4 mm in the center of the sintered body including the joint interface between both sintered bodies) was photographed with a microscope, and voids in this photographed image were observed. The number was extracted by discriminant analysis and the number was counted. The number of holes thus measured was converted to the number of holes per 1 mm ² .

Moreover, in order to confirm the state of the vacancies inside the composite sintered body, cross-sectional vacancies were observed using image analysis software. In cross-sectional hole observation, holes with an area of 80 μm ² or more are extracted within a predetermined observation range (for example, a 0.5 × 0.5 mm region in the center of the sintered body including the joint interface between both sintered bodies). Then, the circularity and needle ratio were measured, and the respective arithmetic mean values were calculated.

  First, the optimum value of the amount of phosphorus added to the composite sintered body was determined. A plurality of types of composite sintered bodies added with iron-phosphorus alloy powder corresponding to the proportion of phosphorus shown in Table 1 were prepared, and the crushing strength and bonding strength were measured. The sintering conditions were a maximum temperature of 1200 ° C. and a maximum temperature holding time of 30 minutes, and were performed in an Ar atmosphere.

As a result, Examples 1 to 4 to which phosphorus was added had higher crushing strength and bonding strength than Comparative Example 1 that did not contain phosphorus, and in particular, as the amount of phosphorus added increased, crushing strength and bonding strength were increased. Improved. Specifically, Examples 1 to 4 showed very high values such as a crushing strength of 1000 MPa or more and a bonding strength of 300 MPa or more. From this result, it became clear that the addition amount of phosphorus in the composite sintered body is desirably 0.2% by mass or more, preferably 0.3% by mass or more. Moreover, the number of holes per unit area in Examples 1 to 4 was 5000 / mm ² or less and 1000 / mm ² or more.

  Next, the optimum value of the sintering conditions for the composite sintered body was determined. The amount of phosphorus added was 0.6% by mass. As for the sintering conditions, the maximum temperature was 1100 ° C. (Comparative Example 2), 1150 ° C. (Example 5), 1175 ° C. (Example 6), 1200 ° C. (Example 4), and 1250 ° C. (Comparative Example 3). The temperature holding time was 30 minutes. Thereafter, the crushing strength and bonding strength of each test piece were measured. The test results under each sintering condition are shown in Table 2 below.

  As a result, Examples 4 to 6 showed high values such as a crushing strength of 1100 MPa or more and a bonding strength of 300 MPa or more. In particular, Example 6 having a sintering temperature of 1175 ° C. showed the highest value in crushing strength and bonding strength.

The number of holes per unit area of each test piece decreased as the sintering temperature increased. On the other hand, the density of these test pieces did not change greatly in the range of 6.75 to 6.85 g / cm ³ . Therefore, if the number of pores per unit area is 5000 / mm ² or less, preferably 4000 / mm ² or less, more preferably 3000 / mm ² or less, the sintering is sufficiently advanced. It was confirmed to have excellent crushing strength and bonding strength. In addition, when the number of holes per unit area was 1000 / mm ² or more, it was confirmed that the extreme progress of sintering was avoided, and excellent crushing strength and bonding strength were obtained.

In addition, the arithmetic average value of the circularity of the internal vacancies of each test piece increases as the sintering temperature rises, and the arithmetic average value of the acicular ratio of the internal vacancies of the cross section of each test specimen is It became smaller as the setting temperature increased. On the other hand, the density of these test pieces did not change greatly in the range of 6.75 to 6.85 g / cm ³ . From this, sintering is sufficient because the arithmetic average value of the circularity of the internal vacancies is greater than 0.2, or the arithmetic average value of the acicular ratio of the internal vacancies is less than 1.9. It was confirmed that it had excellent crushing strength and bonding strength. In addition, since the arithmetic average value of the circularity of the internal vacancies is less than 0.5, or the arithmetic average value of the acicular ratio of the internal vacancies is larger than 1.5, extreme progress of sintering is avoided. It was confirmed that it has excellent crushing strength and bonding strength.

1 1st member 2 2nd member

Claims (15)

A composite sintered body having a first member made of a sintered body containing iron as a main component and a second member diffusion-bonded to the sintered body,
The composite sintered body, wherein the sintered body contains phosphorus and the number of pores per unit area is 5000 / mm ² or less.   The composite sintered body according to claim 1, wherein the second member is made of another sintered body containing iron as a main component.   The composite sintered body according to claim 2, wherein the other sintered body has the same composition as the sintered body of the first member. The composite sintered body according to any one of claims 1 to 3, wherein the number of pores per unit area of the sintered body is 1000 / mm ² or more. 5. The arithmetic average value of the circularity of vacancies of 80 μm ² or more among the internal vacancies of the sintered body is greater than 0.2 and less than 0.5. 5. Composite sintered body. 6. The arithmetic average value of the needle-like ratio of the pores of 80 μm ² or more among the internal pores of the sintered body is greater than 1.5 and less than 1.9. 6. Composite sintered body.   The composite sintered body according to any one of claims 1 to 6, wherein a content of phosphorus in the sintered body is 0.2 mass% or more and 1.0 mass% or less. A compacting step of compressing a raw material powder containing iron as a main component to form a first compact and a second compact;
By heating the first green compact and the second green compact while being pressed against each other, a first sintered body and a second sintered body are obtained, and the first sintered body and the second sintered body are obtained. A method of manufacturing a composite sintered body including a sintering step of diffusion bonding the sintered body,
The raw powder of the first green compact contains phosphorus,
The manufacturing method of the composite sintered compact which made the heating temperature in the said sintering process 1050 degreeC or more. The method for producing a composite sintered body according to claim 8, wherein in the sintering step, sintering proceeds until the number of pores per unit area of the first sintered body is 5000 / mm ² or less.   The method for producing a composite sintered body according to claim 8 or 9, wherein the content of phosphorus in the raw material powder of the first green compact is 0.2 mass% or more and 1.0 mass% or less.   The method for producing a composite sintered body according to any one of claims 8 to 10, wherein the composition of the raw material powder of the first green compact and the second green compact is the same. A compacting process in which a raw powder mainly composed of iron is compressed to form a compact;
The sintered compact is obtained by heating the green compact and the other member in a state where they are pressed against each other, and includes a sintering step of diffusion bonding the sintered body and the other member. A manufacturing method comprising:
The raw powder of the green compact contains phosphorus,
The manufacturing method of the composite sintered compact which made the heating temperature in the said sintering process 1050 degreeC or more. The method for producing a composite sintered body according to claim 12, wherein the number of pores per unit area of the sintered body is 1000 / mm ² or more.   The method for producing a composite sintered body according to claim 12 or 13, wherein a content of phosphorus in the raw material powder of the green compact is 0.2 mass% or more and 1.0 mass% or less. The method for producing a composite sintered body according to any one of claims 8 to 14, wherein a heating temperature in the sintering step is 1200 ° C or lower.