JPH0790301A - Iron-based granulated powder for powder metallurgy and method for producing the same - Google Patents

Abstract

(57) [Summary] [Purpose] Having good flowability and excellent compressibility, variation in packing density and segregation of components are reduced, and high-strength green compacts are obtained. Provides an iron-based granulated powder for powder metallurgy capable of obtaining a sintered product with excellent dimensional accuracy. [Composition] A granulated powder obtained by rolling a mixed powder of an iron-based main component powder and a subcomponent powder and then pulverizing the composite powder of the subcomponent particles 2 in the main component iron-based powder particles 1 Those having a particle size of 80 μm or more and less than 500 μm and a particle size of 44 μm or less are 30% by weight or less, the fluidity of the powder is 25 seconds or less, and the weight reduction rate of the green compact in the ratler test is 1.
An iron-based granulated powder for powder metallurgy, which is 0% or less.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an iron-based powder used in the production of a sintered machine part by a powder metallurgy method, particularly an iron-based granulation for powder metallurgy which is excellent in fluidity and can obtain sufficient green compact strength. TECHNICAL FIELD The present invention relates to a powder and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, iron-based sintering machine parts have been produced by using iron-based mother powders such as iron, carbon steel, and alloy steels containing Cu, Ni, Mn, Mo, which are necessary for obtaining a desired steel composition. A metal powder such as Cr or a graphite powder is mixed, and if necessary, an intermetallic compound such as MnS or a powder of an inorganic compound such as a metal carbide, oxide, or nitride, or a stearic acid compound or molybdenum sulfide. It is manufactured by mixing lubricant powders, compressing and molding these mixed powders, and then sintering.

In the step of producing a green compact from the above-mentioned mixed powder, the mixed powder stored in the hopper is filled in the shoe box through a hose, and the shoe box is moved back and forth on the mold cavity to obtain a metal mold. A method is generally used in which a mixed powder is supplied and filled in a mold cavity, and then the mixed powder is compression-molded by pressing with a mold to obtain a green compact.

By the way, the sintered mechanical parts to be manufactured are required to have good dimensional accuracy, that is, the dimensional change rate during sintering is uniform in each part. However, since the mixed powder does not have sufficient fluidity, it does not flow uniformly in the mold cavity, resulting in variations in packing density. Further, even when powder is fed from the hopper to the shoe box, the mixed powder does not have sufficient fluidity and is likely to be clogged in the hose, which causes unevenness in powder feeding, which causes variations in packing density. As a result of variations in the density of the green compact due to these factors, the rate of dimensional change during sintering varies from part to part of the green compact, resulting in variations in product dimensions and distortion of the product shape.

Therefore, in order to improve the fluidity of the mixed powder, the iron-based mother powder and the other added accessory component powders have been granulated into spherical shapes. Since the irregularities on the surface are extremely small, the powders do not mesh with each other during molding, so the adhesive force of the powders weakens and sufficient green compact strength cannot be obtained, which is not suitable for mass production processes such as damage during handling. There was a problem.

Further, in the above-mentioned mixed powder, since the powder characteristics of the iron-based mother powder and other subordinate component powders are different, the components are mixed when they move from the hopper to the hose or in the shoe box. Segregation occurs every time. This component segregation also causes variations in the dimensional change rate during sintering, resulting in dimensional variations and shape distortions in the obtained products. The above-mentioned variation in packing density and variation in product size and shape due to component segregation occur within individual products or between products.

As a means for solving these drawbacks, Japanese Patent Application Laid-Open No. 4-214801 discloses a method in which an organic binder such as a higher alcohol or a higher fatty acid is used to bond an additive subcomponent powder to an iron-based mother powder to form a component. A method of preventing the segregation of the is proposed. However, in this method, sufficient adhesion between the powders cannot be obtained, and the adhered powders are separated when flowing in the hose or shoe box, so segregation of the components cannot be eliminated, and further the powders cannot be eliminated. The liquidity of is also not improved. Moreover, the increase in density is prevented by the volume of the organic binder during compression molding, and the fluidity of the powder is reduced due to the effect of the organic binder, and the organic binder prevents the powder particles from being entangled with each other, thus reducing the green compact strength. There was a problem.

Further, in Japanese Patent Laid-Open No. 2-145702,
A method for preventing component segregation by partially diffusion-adhering (diffusion bonding) an iron-based mother powder and an added subordinate component powder is disclosed. However, in this method, the additive component powder that can be diffused and adhered is limited to the metal powder, and when the subordinate component other than the metal is added, the component segregation is not reduced at all. Also, solid solution due to diffusion adhesion causes powder hardening, which makes it difficult for plastic deformation during compression molding.
Even if the pressure is increased, the green compact density does not increase sufficiently. Further, since powder entanglement is weakened by the powder curing, there is a problem that the green compact strength decreases.

In addition to these methods, there is mechanical alloying as a method of integrating the accessory component powder with the iron-based mother powder. However, in the granulation process by mechanical alloying using a conventional vibration mill, ball mill, etc., powder hardening occurs due to forced processing, and the compressibility deteriorates due to a decrease in plastic deformability, so a sufficient green compact density cannot be obtained. Further, there is a problem in that the strength of the green compact is reduced because the entanglement between the powders is weakened by the powder curing. Moreover, since the processing in the vibration mill or the ball mill is a batch processing, the productivity is poor and the cost is increased.

[0010]

SUMMARY OF THE INVENTION In view of the above conventional circumstances, the present invention is to disperse subordinate components to be added in a uniform ratio in the iron-based base material as a main component, to obtain good fluidity and compression molding. It is a granulated powder with excellent compressibility, which reduces variations in packing density and segregation of components, and also provides high-strength green compacts by compression molding. An object of the present invention is to provide an iron-based granulated powder for powder metallurgy, which can obtain a solidified product, and a method for producing the same.

[0011]

In order to achieve the above object, the iron-based granulated powder for powder metallurgy provided by the present invention is iron,
An iron-based granulated powder in which secondary component particles are mechanically composite-integrated to form secondary particles in main component particles made of carbon steel or alloy steel, and the average particle size is 80 μm or more and less than 500 μm. Particles having a particle size of 44 μm or less are 30% by weight or less, and have a fluidity of 25 seconds or less per 50 g by a fluidity test specified in JISZ2502, and JSPM 4-
7 ton / cm ² in the Rutler test specified in 69.
The weight reduction rate of the green compact compression-molded in 1. is 1.0% or less.

The above-mentioned iron-based granulated powder of the present invention is obtained by mixing the main component powder of iron, carbon steel or alloy steel with the subordinate component powder,
The mixed powder is powder-rolled to obtain a plate-shaped compact, which is crushed to form a granulated powder of secondary particles in which main component particles are mechanically composite-integrated with secondary component particles. It can be manufactured by a method of classifying the particles having an average particle size of 80 μm or more and less than 500 μm and a particle size of 44 μm or less to 30% by weight or less.

Here, the subordinate component means a component added to an iron-based mother powder such as iron, carbon steel or alloy steel in order to obtain a sintered product having a desired steel composition, for example, Cu, Ni. , M
Metals such as n, Mo and Cr, and graphite are the main ones,
Other examples include intermetallic compounds such as MnS, inorganic compounds such as metal carbides, oxides, nitrides and borides, and lubricants such as stearic acid compounds and molybdenum sulfide. Incidentally, iron, carbon steel, and alloy steel as the main components are used in the usual sense, and any of them may contain inevitable impurities.

[0014]

In the granulated powder of the present invention, as shown in FIG. 1, the subordinate component particles 2 are uniformly incorporated in the iron-based powder particles 1 as the main component in a proportion according to the blending ratio, and mechanically In addition to being composite integrated, its particle size distribution is optimized, so it has excellent fluidity and reduces component segregation at the same time as compared with the conventional mixed powder of main component powder and subordinate component powder.
Compared to the conventional granulated powder that is compositely integrated by mechanical alloying, the powder has excellent compressibility and the strength of the green compact can be increased.

Therefore, by using the granulated powder of the present invention, it is possible to easily obtain a green compact which is more uniform in both density and composition than ever before, and by sintering the green compact. A sintered product excellent in shape and dimensional accuracy can be manufactured and provided at low cost.

In the present invention, the average particle size of the granulated powder is 8
The reason why the size is 0 μm or more and less than 500 μm is that the average particle size is
When it is less than 0 μm, the fluidity cannot be improved as compared with the conventional mixed powder or granulated powder, and when it is 500 μm or more, the packing density does not increase when it is supplied to the mold, and the compressibility decreases and a high pressure is applied. This is because the density of the green compact does not increase without it. In addition, 30 of the granulated powders have a particle size of 44 μm or less.
If it exceeds the weight%, fine particles tend to easily enter the gaps between the molds, and the molds may stick to each other in a short time, shortening the mold life and impairing the productivity.

The above-mentioned granulated powder of the present invention has excellent fluidity, and the fluidity according to the fluidity test specified in JIS Z2502 is 25 seconds or less per 50 g. This fluidity is 2
If it exceeds 5 seconds, it becomes difficult to evenly fill the granulated powder in the respective parts in the mold cavity, and the local deviation of the density in the green compact becomes large. In order to improve the fluidity, it is possible to process the powder into a spherical shape, but in that case, the irregularities on the powder surface are reduced, so the powders do not become entangled during compression molding, and sufficient green compact strength is obtained. What cannot be obtained is as described above.

The granulated powder of the present invention has a certain degree of unevenness on the particle surface, and when pressure is applied during compression molding, the mechanical bond of the powder is decomposed into primary particles, and primary particles having unevenness on the surface are formed. Entanglement of particles easily occurs. Therefore, the green compact of the granulated powder of the present invention can obtain higher strength than the green compact of the conventional granulated powder.
7ton / cm in the Rutler test specified in -69
The weight reduction rate (Rattler value) of the green compact compression-molded in ² becomes 1.0% or less. When the ratler value exceeds 1.0%,
The green compact is liable to chip, making it difficult to maintain the shape during handling.

In the method for producing a granulated powder according to the present invention, a mixed powder of an iron-based mother powder as a main component powder and a subordinate component powder is continuously formed into a plate shape by using, for example, a roller type powder rolling device. After shaping into, crush it with a crusher,
Adjust the particle size distribution by sieving. Therefore, even in the case of mechanical granulation, powder hardening such as mechanical alloying does not occur, the compressibility of the powder is improved, and at the same time, the strength of the green compact is improved. Moreover, since the powder remaining after the particle size distribution adjustment can be recovered and reused, the raw material loss is small,
The granulated powder can be continuously produced at low cost.

The subordinate component powder added to the iron-based main component powder preferably has an average particle size of 50 μm or less. If the average particle size exceeds 50 μm, coarse outflow holes will be formed when the subcomponents form a solid solution during sintering, which will adversely affect dimensional accuracy and sinterability, and This is because they are easy to peel off. Further, when the total amount of the subordinate powder exceeds 30% by weight of the total mixed powder, the subordinate components are likely to agglomerate and cause segregation of the components.

Further, by annealing the granulated powder that has been granulated and classified according to the above-mentioned manufacturing method, the processing strain in the powder caused by the mechanical granulation treatment is removed, and the granulated powder is further softened and annealed. The compressibility and green compact strength can be improved more than before.

By using the iron-based granulated powder of the present invention, a green compact having a uniform composition and high density and high strength can be obtained. By sintering the green compact,
It is possible to obtain a sintered product with less shape distortion and dimensional variation. As a result, it is possible to simplify the processing steps and reduce the raw material loss as compared with the conventional products, and even if the thin-walled product is prone to uneven thickness or deformation, and to easily cause defects due to insufficient strength of the green compact. , Easy to manufacture high quality products.

Although the iron-based granulated powder of the present invention can be molded and sintered alone, a high-precision sintered body can be obtained by mixing it with an iron-based mother powder. Can be manufactured more economically. In that case, if the ratio of the iron-based mother powder exceeds 80% by weight, problems of fluidity and component segregation occur, so the ratio of the iron-based granulated powder of the present invention is preferably 20% by weight or more.

[0024]

Example 1 As an iron-based mother powder of the main component powder, F having an average particle size of 90 μm was used.
e powder with the same average particle size and a composition of Fe-4 wt% Ni-
An alloy steel powder of 0.5 wt% Mo-1.5 wt% Cu was prepared. According to these iron-based mother powders, the component powders were added and mixed at the ratios shown in Table 1 below, the mixed powders were molded into a plate shape by a roller type powder rolling device, and the molded body was crushed by a crusher.

[0025]

[Table 1] Metal powder Graphite powder Inorganic compound Lubricant sample Mother powder (wt%) (wt%) (wt%) (wt%) 1 Fe 2% Cu (35 μm) 0.6% C − 0.8% Zinc stearate 2 Fe 2% Cu (60 μm) 0.6% C − 0.8% Zinc stearate 3 Alloy steel − 0.6% C 0.5% MnS 0.8% Zinc stearate 4 Fe 4% Ni 0.6% C 15% FeMo 0.8% Zinc stearate 5 Fe 4% Ni 0.5% Mo 0.6% C 15% Al ₂ O ₃ 0.8% Zinc stearate 1.5% Cu (35 μm) (Note) The average particle size of the subordinate component powder is; C powder: 15 μm, M
nS powder: 20 μm, FeMo powder: 20 μm, Al ₂
O ₃ powder: 15 μm, Ni powder: 30 μm, Mo powder:
30 μm (Cu powder is added in the table)

With respect to each of the obtained Fe-based granulated powders, the elemental analysis of the Fe powder particles, which is the main component extracted by magnetic separation, was carried out, and the amount of the subordinate component elements complex-integrated with the Fe powder particles was investigated. Analytical value / subcomponent addition amount) × 100
The degree of attachment of the secondary component element defined by (%) was determined.
Table 2 shows the degree of attachment of subordinate component elements obtained for the granulated powder of each sample.

[0027]

[Table 2] Degree of secondary component element adhesion (%) Sample Cu C Mn Ni Al Al Mo 1 73 70 − − − − 2 50 75 − − − − 3 97 75 68 98 − 95 4 − 73 − 74 − 69 5 67 72 − 65 75 66

In the case of a usual iron-based mixed powder, the degree of adhesion of the added subordinate element is very small, for example, the degree of Cu adhesion is only about 6%, so that in the granulated powder produced according to the method of the present invention, The degree of adhesion of the constituent elements is much higher. However, since the average particle size of the added Cu powder was large in Sample 2, the adhesion degree of Cu was smaller than that in Sample 1.
From the above results, in the granulated powder according to the method of the present invention, it was found that the component segregation in the powder is significantly improved. It is understood that the segregation of the components can be significantly improved as compared with the case where the normal mixed powder is used.

A scanning electron micrograph of the obtained granulated powder of Sample 1 is shown in FIG. Moreover, the characteristic X peculiar to the constituent elements of the granulated powder is obtained by the irradiation of the electron beam with the scanning electron microscope.
Since a line is generated, the distribution state of each constituent element can be known from this X-ray. The analysis for obtaining the distribution state of the constituent elements by this scanning electron microscope is called elemental surface analysis. An X-ray photograph of the granulated powder of sample 1 obtained by elemental surface analysis is shown in FIG. 3 for Cu and FIG. 4 for Fe. Are shown respectively. From these FIG. 2 to FIG. 4, Cu which is a subordinate component
It can be seen that Fe is compositely integrated with the powder particles of Fe, which is the main component, and uniformly dispersed.

Example 2 The granulated powders of Sample 1, Sample 3 and Sample 4 obtained in Example 1 were sieved so as to have a particle size distribution shown in Table 3 below.

[0031]

Table 3 The average particle size granulated powder powder particle size distribution (wt%) specimen (μm) ≦ 44 44 <~ ≦ 106 106 <~ ≦ 150 150 <~ ≦ 500 500 <1-a 90 20 60 20 − − 1−b * 90 40 40 20 − − 1−c * 500 − 5 15 30 50 1−d * 70 30 70 − − − 3−a 90 20 60 20 − − 4−a 90 20 60 20 − − 5-a 90 20 60 20 − − (Note) Samples marked with * in the table are comparative examples.

Regarding the granulated powder of each sample in Table 3, JIS
The fluidity per 50 g of the powder by the fluidity test defined by Z2502, the apparent density defined by JIS Z2504, and the green compact density when the powder is compressed at 7 ton / cm ² in the compressibility test defined by JSPM 1-64. Was measured and the obtained results are shown in Table 4. For reference, the above-mentioned test results are also shown in Table 4 for the mixed powder of Sample 1 before granulation in Example 1.

[0033]

[Table 4] (Note) Samples marked with * in the table are comparative examples or reference examples.

Each of the granulated powders of the present invention has excellent fluidity, and for example, the fluidity of the granulated powder of the present invention of Sample 1-a is significantly improved as compared with the mixed powder of Sample 1 before granulation. I understand. Comparing the behaviors during powder flow, the mixed powder of Sample 1 before granulation is a funnel flow in which only the powder in the center of the funnel first flows down from the orifice and the powder near the wall remains behind. The granulated powder of the present invention has a mass flow that flows down from the entire funnel toward the orifice, resulting in a more preferable flow behavior.

Further, with each of the granulated powders of the present invention, seizure of the mold did not occur even after 1000 continuous molding, whereas granulation of sample 1-b containing a large amount of fine powder having a particle size of 44 μm or less As the powder is easy to get fine powder between the die and punch,
Seizure between molds occurred in 350 continuous moldings.
Further, in the case of the granulated powder of Sample 1-c having an average particle diameter of 500 μm, the green compact density did not increase, and Sample 1 having an average particle diameter of 70 μm
It can be seen that the granulated powder of -d has extremely poor fluidity.

Example 3 A mixed powder of sample 1 before granulation in the above-mentioned Example 1, a vibration mill powder obtained by mechanically alloying the mixed powder of the same sample 1 with a vibration mill, and a sample 1 whose particle size was adjusted in Example 2
For the granulated powder of the present invention of a and the annealed granulated powder of the present invention in which the granulated powder of Sample 1-a is further annealed at 600 ° C. for 1 hour, the ratler test specified in JSPM 4-69. The weight loss rate (Rattler value) of the green compact obtained by compressing the powder at 7 ton / cm ² was measured, and the obtained results are shown in Table 5 together with the density of each green compact.

[0037]

TABLE 5 Powder (Sample 1 standard) mixed powder vibrating mill powder granulated powder annealing granulated powder compact density ^{(g / cm 3) 7.10 6.45} 7.10 7.18 Ratora value (%) 0.70 3.05 0.70 0.69

The vibrating mill powder has a lower green compact density due to deterioration in compressibility than the ordinary mixed powder, and has a Ratler value of 3.05%, which is extremely larger than that of the ordinary mixed powder. No powder strength was obtained. In contrast,
The granulated powder of the present invention has a ratler value that is almost the same as a normal mixed powder, and the granulated powder obtained by annealing this granule powder has some improvement in compressibility and ratler value, and has sufficient green compact strength. It was found that

Example 4 The usual mixed powder before granulation in the sample 1 of the above-mentioned Example 1 and the granulated powder of the present invention in the sample 1-a obtained in Example 2 were
Filling a mold with an outer diameter of 40 mm and an inner diameter of 27 mm,
Compression molding was performed at a pressure of 7 ton / cm ² to form 30 ring-shaped green compacts. Each green compact was divided into four equal parts and the respective densities were measured, and the standard deviation σ of all the values was compared. Standard deviation σ of split green compact density for normal mixed powder
Was 0.025 g / cm ³ , whereas the standard deviation σ of the granulated powder of the present invention was 0.015 g / cm ³ , showing that the density variation of the green compact was reduced.

Further, an ordinary mixed powder of Sample 1 in Example 1, the granulated powder of Sample 1-a obtained in Example 2 of the present invention, and an auxiliary subcomponent powder added with an organic binder were used as iron-based mother powders. Using a conventional binder adhesive powder having the same composition as that of Sample 1 adhered to the above, ring-shaped green compacts formed in the same manner as above were used, respectively, in a mixed gas atmosphere of 75% H ₂ -25% N _{2 at} 1130 ° C. for 20 minutes. Sintered for minutes. With respect to each of the 20 ring-shaped sintered bodies thus obtained, the outer diameter dimension was measured at four locations at 45 ° intervals, and the variation 4σ in the outer diameter dimension was determined from the standard deviation σ of all the values.

FIG. 5 shows a comparison of variations 4σ in the outer diameter of the sintered bodies produced by using the above-mentioned three kinds of powders. The variation 4σ in the outer diameter of the sintered body is 0.019 mm in the case of the normal mixed powder, and 0 in the case of the conventional variation adhesion powder in which the additive subordinate component powder is adhered to the iron-based mother powder using the organic binder. Sample size 1 is 0.016 mm
In the granulated powder of the present invention of -a, which is far smaller than 0.010 mm, the component segregation and density distribution in the granulated powder and in the green compact are improved, and as a result, the dimensional variation of the sintered body is reduced. I understand.

Example 5 In the sample 1 of the example 1, the addition amounts of the Cu powder and the C powder, which are subordinate components, were both quadrupled, and the same granulation treatment as in the example 1 was performed. The granulated powder of the present invention was produced by adjusting to the same particle size distribution as 1-a. 25% by weight of the obtained granulated powder and the Fe powder 7 used in Example 1
Sample 1 of Example 2 by mixing with 5% by weight
Fe having the same composition and the same particle size distribution as a for powder metallurgy
The raw material powder was used.

The fluidity of this raw material powder was measured according to JIS Z250.
The fluidity test specified in No. 2 was performed in the same manner as in Example 2, and the strength of the green compact formed from this raw material powder was measured by the JSPM method.
According to the Ratler test specified in 4-69, a Ratler value was measured in the same manner as in Example 3, and further, in the same manner as in Example 4, the outer diameter was 40 mm and the inner diameter was 27 mm produced from this raw material powder.
The variation 4σ in the outer diameter of the ring-shaped sintered body was calculated.

Comparing the respective measurement results obtained for the raw material powder of the present invention with the same measurement results for the mixed powder before granulation in Sample 1 of Example 1 having the same composition as Sample 1-a, The fluidity is 30 seconds for the mixed powder and 25 seconds for the raw material powder, and the ratler value is 0.70% for the mixed powder.
On the other hand, the raw material powder was 0.75%, and the outer diameter variation 4σ was 0.019 mm in the mixed powder and 0.012 mm in the raw material powder. From this result, it is understood that by using the raw material powder of the present invention, it is possible to economically manufacture an iron-based sintered product with improved dimensional accuracy without substantially lowering the green compact strength.

[0045]

According to the present invention, secondary components such as metals, graphite, inorganic compounds, and lubricants to be added are dispersed in the iron-based base material as the main component in a uniform ratio, and good fluidity is obtained. It is possible to provide an iron-based granulated powder for powder metallurgy, which has excellent compressibility during compression molding and can be made into a high-strength green compact by compression molding.

Therefore, by using the iron-based granulated powder of the present invention, it is possible to obtain a green compact which has reduced variations in packing density and segregation of components and is excellent in density and strength.
By sintering this green compact, it is possible to manufacture an iron-based sintered product with excellent dimensional accuracy and shape.

[Brief description of drawings]

FIG. 1 is a conceptual schematic diagram for explaining granulated powder particles of the present invention.

FIG. 2 is a photograph (250 times) of the particle structure of the granulated powder of the present invention observed with a scanning electron microscope.

FIG. 3 is an elemental plane analysis X-ray photograph (250 showing a state of distribution of Cu in the granulated powder of FIG. 2 analyzed by using a scanning electron microscope.
Times).

FIG. 4 is an elemental surface analysis X-ray photograph (250 of the distribution state of Fe in the granulated powder of FIG. 2 analyzed by a scanning electron microscope).
Times).

FIG. 5 is a graph showing the outer diameter dimensional accuracy of each sintered body produced from the granulated powder of the present invention, the conventional mixed powder, and the organic binder adhesive powder.

[Explanation of symbols]

 1 Iron-based powder particles 2 Secondary component particles

Claims (6)

[Claims] 1. An iron-based granulated powder, wherein secondary component particles are formed by mechanically compounding and integrating secondary component particles into main component particles made of iron, carbon steel or alloy steel, and having an average particle size of 80 μm
30% by weight or less of particles having a particle size of 44 μm or less and less than 500 μm, a flow rate of 25 seconds or less per 50 g by a flow rate test specified in JIS Z2502, and 7 ton in a ratler test specified in JSPM 4-69. An iron-based granulated powder for powder metallurgy, wherein the weight reduction rate of the green compact compression-molded at 1 / cm ² is 1.0% or less. 2. The secondary component particles are at least one selected from metals other than iron, graphite, inorganic compounds, and lubricants, and the total amount thereof is 30% by weight or less. 1. An iron-based granulated powder for powder metallurgy according to 1. 3. A main component powder made of iron, carbon steel or alloy steel is mixed with a main component powder, and the mixed powder is powder-rolled to obtain a plate-shaped compact, which is crushed to obtain a main component particle. The granulated powder of the secondary particles in which the component particles are mechanically compounded and integrated is prepared, and then the granulated powder is classified to have an average particle size of 80 μm or more.
3 with a particle size of less than 00 μm and a particle size of 44 μm or less
A method for producing an iron-based granulated powder for powder metallurgy, which comprises 0% by weight or less. 4. The auxiliary component powder is at least one selected from metals other than iron, graphite, inorganic compounds, and lubricants, and the total amount of the auxiliary component powders added is 30 of the total mixed powder.
The method for producing an iron-based granulated powder for powder metallurgy according to claim 3, characterized in that the content is at most wt%. 5. The iron-based granulated powder for powder metallurgy according to claim 3, wherein the subordinate component powder has an average particle size of 50 μm or less. 6. The method for producing an iron-based granulated powder for powder metallurgy according to claim 3, wherein the classified granulated powder is further annealed.