JPH10280083A - Iron-base powder mixture for powder metallurgy use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an iron-base powder mixture for powder metallugy use, capable of producing a sintered compact excellent in machinability and sliding characteristic by mixing, with an atomized iron powder containing specific amounts of Mn, a powder of compound containing specific amounts of B and a powder of S-containing compound or further a graphite powder, a copper powder, a lubricant, etc. SOLUTION: The iron-base powder mixture for powder metallurgy use is obtained by mixing a B-containing compound powder and an S-containing compound powder or further a graphite powder, a copper powder, and a lubricant with an iron powder. It is preferable to use, as the above iron powder, an atomized iron powder containing 0.05-0.40 wt.% Mn and further containing, if necessary, as an alloy component for improving strength, 0.5-7.0% Ni or 0.05-6.0% Mo in partially alloyed state. As to the B-containing compound, its mixing amount is 0.001-0.3% expressed in terms of B, and H3 BO3 , B2 O3 , BN, etc., are used. As to the S-containing compound, its mixing amount is 0.03-0.3% expressed in terms of S, and S, FeS, MnS, etc., are properly used. Further, preferred mixing amounts of the graphite powder and the copper powder are 0.05-3.0% and <= about 4%, respectively, and proper amounts of zinc stearate, etc., are used as the lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-based mixed powder for powder metallurgy, and in particular, exhibits excellent machinability and sliding properties even as a sintered body, and even when containing Ni, Mo, Cu, etc. The present invention relates to an iron-based mixed powder for powder metallurgy that can be straightened as it is.

[0002]

2. Description of the Related Art In general, powder metallurgy is a technique in which a metal powder is pressurized in a mold to form a compact, and then sintered to produce a machine part or the like. For example, when iron powder is used for the metal powder, Cu powder, graphite powder, etc. are mixed with the iron powder, molded and sintered, and usually a sintered body having a density of about 5.0 to 7.2 g / cm ³ is obtained. I do. If such a powder metallurgy method is used, a mechanical part having a considerably complicated shape can be manufactured with high dimensional accuracy. But,
When manufacturing machine parts with stricter dimensional accuracy,
The sintered body may be further subjected to machining such as cutting or drilling.

[0003] Further, since the sintered body is generally inferior in machinability, a tool used for cutting is in comparison with a case of cutting an ingot (for example, a material obtained by rolling a slab manufactured by continuous casting). Life is shortened. Therefore, there arises a problem that the cost for machining becomes high. The cause of the low machinability of the sintered body lies in the pores contained in the sintered body. This is because the pores cause intermittent cutting, or the thermal conductivity of the sintered body is reduced, and the temperature of the cut portion is increased.

Therefore, in order to improve the machinability of the sintered body,
Conventionally, S and MnS have often been mixed with iron powder. This is because S or MnS facilitates breakage of chips or forms a thin film of S or MnS on the tool rake face, and the thin film exerts a lubricating action during cutting. For example, Tokufair
No. 3-25481 discloses that Mn is 0.1 to 0.5 wt%,
Iron powder for powder metallurgy has been proposed, which is produced by atomizing molten steel obtained by adding 0.03 to 0.07% by weight of S to pure iron containing C or the like with water or gas. However, the machinability of a sintered body manufactured using this iron powder has been improved by only about two times less than that of a sintered body manufactured using conventional iron powder, and further improvement has been demanded.

[0005] Also, JP-A-7-233401, JP-A-7-23
No. 3402 proposes an atomized steel powder containing S, Cr and Mn, but when this steel powder is sintered, graphite remains in the pores of the sintered body, and at the same time, MnS becomes contained in the iron particles. It is said to precipitate and dramatically increase the machinability of the sintered body. In addition,
It is believed that this residual graphite occurs during sintering because Cr and S suppress the diffusion of graphite in the iron powder particles.

However, even with such steel powder, if the atmosphere gas during sintering contains H ₂ , there is a problem that the cutability and abrasion resistance of the sintered body are reduced. Improvement was aspired. Further, JP-A-8-176604
In the official gazette, B: 0.001 to 0.03 wt%, Cr: 0.02 to 0.07 wt%
%, Mn: less than 0.1 wt%, at least one of S, Se, Te
By sintering iron powder containing 0.03-0.15wt%,
It is disclosed that the amount of residual graphite is further increased and the machinability is improved. However, in the technique disclosed in Japanese Patent Application Laid-Open No. 8-176604, the amount of residual graphite is at most about 0.42 wt%, and iron powder capable of retaining a larger amount of graphite in a sintered body is desired. Was rare.

On the other hand, when a gear as an automobile part requiring high strength and high fatigue properties is manufactured by a powder metallurgy method, a method of adding an alloy element to improve strength and fatigue properties is generally used. It is. For example, Japanese Patent Publication No. 45-964
In JP-A-9, powder such as Ni, Cu, or Mo is added as an alloy component to pure iron powder by diffusing and attaching. Although the steel powder produced by this method is excellent in compressibility and strength of the sintered body, since the hardness of the sintered body is high, there is a problem that straightening after sintering is almost impossible and the machinability is poor. .

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a sintered body exhibiting more excellent machinability and sliding characteristics, and a high strength sintered body containing an alloy element. An object of the present invention is to provide a powder mixture for powder metallurgy capable of producing a sintered body having excellent machinability and sliding properties capable of correcting after sintering.

[0009]

Means for Solving the Problems The present inventors disclosed in Japanese Patent Laid-Open No.
With reference to the description in Japanese Patent No. 176604, intensive studies were conducted to further improve the machinability and sliding properties of the sintered body. As a result, it was found from the morphological analysis of B that the iron powder containing B had a new finding that almost 100% of B in the iron powder was segregated as boric acid on the surface of the iron powder. Therefore, boric acid powder, S powder, graphite powder and a lubricant were added to and mixed with iron powder, and the mixture was molded and sintered to produce a sintered body.
New finding that the amount of free graphite in the obtained sintered body increases as compared with the case where a molded body composed of iron powder, graphite powder and a lubricant containing sintering is sintered. It has also been found that when the amount of free graphite exceeds 1% by weight, the sliding characteristics are remarkably improved.

Further, the present inventors have found that the properties are further improved when a segregation preventing treatment is applied and a compound containing B and a compound containing S are adhered on the surface of iron powder. The present invention has been made based on the above findings. That is, the present invention is an iron-based mixed powder for powder metallurgy obtained by mixing iron powder, compound powder containing B, compound powder containing S, or further graphite powder, or graphite powder and a lubricant, The compound powder containing B is composed of one or more compound powders containing B, and the compound powder containing S is one or more.
A compound powder containing at least one kind of S, wherein the compound powder containing B is in a weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound powder containing S, and further the graphite powder. 0.001 to 0.3% in terms of B, and the compound powder containing S is further added to the iron powder, the compound powder containing B, the compound powder containing S, or the weight of the total amount of the graphite powder. And an iron-based mixed powder for powder metallurgy characterized by being mixed in an amount of 0.03 to 0.3% in terms of S.

Further, in the present invention, the iron powder is contained in a
It is preferable to use atomized iron powder containing Mn: 0.05 to 0.40%, the balance being Fe and unavoidable impurities. Further, the iron powder contains, by weight%, Mn: 0.05 to 0.40%,
Further, it may be an atomized iron powder containing one or two selected from Ni: 0.5 to 7.0% and Mo: 0.05 to 6.0%, with the balance being Fe and unavoidable impurities. % By weight, atomized iron powder containing Mn: 0.05 to 0.40%, the balance being Fe and unavoidable impurities;
Ni: 0.5 to 7.0%, Cu: 0.5 to 7.0%, and Mo: 0.
Iron powder obtained by partially alloying one or more selected from 05 to 3.5% may be used.

The present invention also relates to an iron powder for powder metallurgy obtained by mixing iron powder, a compound powder containing B, a compound powder containing S, copper powder, or graphite powder, or graphite powder and a lubricant. A base mixed powder, wherein the compound powder containing B is made of one or more compound powders containing B, and the compound powder containing S is made of one or more compound powders containing S, and contains the B The compound powder is 0.001 to 0.3% in terms of B in weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound powder containing S, the copper powder, and the graphite powder. The compound powder containing the iron powder, the compound powder containing B and the compound powder containing S, or 0.03 to 0.3% in terms of S in terms of S in terms of the total amount of the graphite powder, and the copper powder. Of iron-based mixed powder for powder metallurgy, wherein 4% or less of The, in weight%, Mn: 0.05~0.
It is preferable to use atomized iron powder containing 40%, the balance being Fe and unavoidable impurities.

In the present invention, the iron powder may be an iron powder having the compound powder containing B and the compound powder containing S adhered to the surface. Also, the present invention relates to iron powder,
A step of mixing a compound powder containing B, a compound powder containing S, or further a graphite powder, or a graphite powder and a lubricant or, if necessary, a copper powder to form a mixed powder, and press-forming the mixed powder; A method for producing a sintered body, comprising sequentially performing a step of forming a green compact and a step of sintering the green compact, wherein the compound powder containing B is formed from a compound powder containing one or more types of B. Become
The compound powder containing B is 0.001 to 0.3% in terms of B in weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound containing S, the graphite powder, and the copper powder. The compound powder containing S is 0.03 to 0.3% in terms of S in weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound powder containing S, the graphite powder, and the copper powder. A method for producing a sintered body characterized by mixing.

The present invention also provides a process of mixing a compound powder containing B, or further a graphite powder and, if necessary, a copper powder with iron powder to form a mixed powder, and adding a lubricant to the mixed powder. Further, a step of mixing, a process of forming a green compact by processing, and a step of sintering the green compact, a method of manufacturing a sintered body sequentially performed, wherein the iron powder, The compound powder containing B comprises one or more compound powders containing B,
The compound powder containing B is, by weight% with respect to the total amount of the iron powder, the compound powder containing B, the graphite powder, and the copper powder,
0.001 to 0.3% in terms of B, and furthermore, the compound powder containing S is further added to the iron powder, the compound powder containing B, the compound powder containing S, the graphite powder, and the copper powder by weight%. The step of mixing 0.03 to 0.3% in terms of S to form the mixed powder is a primary mixing step in which a liquid fatty acid is added to the iron powder at room temperature and mixed, and then a compound containing B is added to the primary mixed powder. Secondary mixing step of adding and mixing powder and compound powder containing S, graphite powder, and copper powder and metal soap, which are added as necessary, and increasing the temperature during or after the secondary mixing to obtain fatty acid and metal soap. A tertiary mixing step of forming and mixing a co-melt with the above, and a quaternary mixing step of adding and mixing metal soap or wax at the time of cooling after the tertiary mixing step may be sequentially performed to obtain a mixed powder.

Further, in the present invention, instead of the secondary mixing step, a compound powder containing B, a compound powder containing S, and a metal soap are added to the primary mixed powder and mixed, and the fourth mixing step is performed. Alternatively, a graphite powder, a copper powder to be added as needed, and a metal soap or wax may be added and mixed at the time of cooling after the tertiary mixing step. Further, in the present invention, the step of forming the mixed powder includes, in the iron powder, a compound powder containing B, a compound powder containing S, a graphite powder, and two or more kinds of waxes having melting points different from those of copper powder added as necessary. A primary mixing step of adding and mixing, and a secondary mixing step of raising the temperature during or after the primary mixing to generate a partial melt of the wax and then mixing, and then cooling and fixing the partial melt by cooling. And a tertiary mixing step in which a compound powder containing at least B is fixed on the surface of the iron powder particles, and a metal soap or wax is added and mixed during cooling. Further, in the present invention, instead of the primary mixing step, a compound powder containing B and a compound powder containing S and two or more kinds of waxes having different melting points are added to and mixed with iron powder, and instead of the tertiary mixing step, Alternatively, a step of adding a graphite powder, a copper powder to be added as required, and a metal soap or wax at the time of cooling and mixing may be used.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The iron-based mixed powder of the present invention comprises:
Compound powder containing B, compound powder containing S, or further graphite powder, or graphite powder and a lubricant, and further, if necessary, copper powder. In the sintered body using the mixed powder of the present invention, although the exact mechanism is unknown, mutual interaction between S in a compound containing S such as S, FeS, and MnS and B contained in a compound containing B is considered. It is considered that free graphite is easily generated by the action. This is because even if a sintered body is produced by mixing a pure iron powder having a low S content (S = 0.02 wt%) and a compound containing B, no free graphite is generated in the sintered body. It can be inferred from this. If the mixing amount of the compound powder containing S and the compound powder containing B is limited to the range of the present invention, Ni, Cu, Mo, etc. are added to iron powder by partial alloying, or Ni, Mo is added by pre-alloying. However, the effect that free graphite is easily generated does not change. This free graphite improves the machinability of the sintered body, and also improves the sliding characteristics of the sintered body due to the self-lubricating action of the free graphite.

That is, in the present invention, in order to further improve the machinability and the sliding characteristics, an iron powder, a compound powder containing B,
It is important to produce a sintered body by mixing a compound powder containing S, or further, a graphite powder, or a graphite powder, a lubricant and, if necessary, a copper powder. Next,
The reason for limiting the present invention will be described.

[0018] The iron powder is preferably expressed in terms of% by weight, preferably Mn: 0.05 to
It is preferable to use atomized iron powder containing 0.40% with the balance being Fe and unavoidable impurities. Mn content in iron powder: 0.05 to 0.40% Mn is an element that reduces the amount of free graphite in the sintered body.
For this reason, when Mn is contained in an amount of 0.40% or more, the amount of free graphite in the sintered body decreases, and the machinability and sliding characteristics of the sintered body decrease. Further, it is desirable to reduce Mn as much as possible, but the lower limit of Mn is set at 0.
05%. The preferred range is 0.07 to 0.15%.

If necessary, one or two selected from Ni: 0.5 to 7.0% and Mo: 0.05 to 6.0% may be added to the atomized iron powder. Ni, Mo
May be pre-alloyed and added to increase the strength of the sintered body. If Ni is less than 0.5% and Mo is less than 0.05%, no improvement in the strength of the sintered body is observed. Ni is 7.0%, Mo is
If the content exceeds 6.0%, the machinability of the sintered body rapidly decreases and it becomes difficult to correct. Therefore, when adding a pre-alloy, Ni is limited to the range of 0.5 to 7.0% and Mo is limited to the range of 0.05 to 6.0%. did.

The atomized iron powder is obtained by drying raw powder obtained by spraying molten steel adjusted to a predetermined composition in the above range with high-pressure water,
Further, it is subjected to a reduction treatment and pulverized and classified to be manufactured. Drying and reduction treatments may be performed under ordinary conditions, and are not particularly limited.
Further, if necessary, Mn: 0.05 to 0.40% is contained and the balance Fe
And atomized iron powder consisting of unavoidable impurities, by weight, Ni: 0.5 to 7.0%, Cu: 0.5 to 7.0%, and Mo:
One or more selected from 0.05 to 3.5% may be partially alloyed and added.

Ni, Cu and Mo are added to atomized iron powder,
It is preferable to add Ni, Cu, Mo powder or MoO ₃ powder by mixing and diffusing and adhering them by heat treatment to form a partial alloy.
Ni, Cu and Mo are added in order to increase the strength of the sintered body, but when they are added after being partially alloyed, Ni: 0.5 to 7.
One or more selected from 0%, 0.5 to 7.0% Cu and 0.05 to 3.5% Mo are added. If the content of each element is less than the lower limit, no improvement in the strength of the sintered body is observed. If the content exceeds the upper limit, the machinability of the sintered body is sharply reduced, and it is difficult to correct the sintered body.

After bright quenching and carburizing heat treatment, free graphite partially re-dissolves in the iron particles to form a structure mainly composed of bainite and martensite, and high strength is obtained. Compounding amount of compound powder containing B: 0.001 to 0.3% in terms of B Compounding amount of compound powder containing B is iron powder, compound powder containing B and compound powder containing S, or further, graphite powder and if necessary. By weight% based on the total amount with the added copper powder,
0.001 to 0.3% in B conversion.

As the compound powder containing B, oxides of B,
B nitrides, borates and the like are preferred. Above all, B
₂ O ₃ , H ₃ BO ₃ , ammonium borate and hexagonal BN are preferred. It is preferable that one or more compound powders containing B are mixed and blended. One or more compound powders containing B in B conversion
When the content is 0.001% or more, the amount of free graphite in the sintered body increases remarkably, so that the machinability and sliding characteristics of the sintered body are further improved. On the other hand, the compounding amount of the compound powder containing B is
If it exceeds 0.3%, the compressibility decreases. Therefore, the amount of the compound powder containing B to be added is limited to the range of 0.001 to 0.3% in terms of B.

Compounding amount of compound powder containing S: 0.03 in S conversion
The compounding amount of the compound powder containing 0.3 to 0.3% S is a weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound powder containing S, and further the graphite powder and the copper powder added as needed. S
0.03 to 0.3% in conversion. The compound containing S has an effect of increasing the amount of free graphite in the sintered body. If the compounding amount of the compound powder containing S is less than 0.03% in terms of S, the effect of increasing the amount of residual graphite is not recognized. On the other hand, if it exceeds 0.3%, "soot" is generated at the time of sintering, and the mechanical parts as products tend to rust. For this reason, the compounding amount of the compound powder containing S is limited to 0.03 to 0.3% in terms of S.

Compounding amount of graphite powder: 0.5 to 3.0% The compounding amount of graphite powder is the total amount of iron powder, compound powder containing B, compound powder containing S, graphite powder, and copper powder added as necessary. It is preferably from 0.5 to 3.0% by weight based on the weight. Graphite powder is added as a graphite source for leaving graphite in pores after sintering to improve sliding characteristics and machinability, and also for dissolving in iron to further enhance strength. If it is less than 0.5%, the sliding properties and strength are reduced, while if it exceeds 3.0%, the pearlite ratio increases and the machinability decreases.

The amount of copper powder: 4% or less The amount of copper powder (Cu powder) is iron powder, compound powder containing B, S
Is preferably 4% by weight or less based on the total amount of the compound powder, graphite powder and copper powder containing Cu powder is added as necessary to increase the strength without lowering the machinability. If it exceeds 4%, the machinability decreases. Preferably, 1% or more is added.

Next, a lubricant is preferably added to 100 parts by weight of the above-mentioned iron powder, compound powder containing B, graphite powder, compound powder containing S, and copper powder added as required.
Add 2.0 parts by weight or less and add 1 part by the usual method such as V blender.
It is preferable to mix each time. As the lubricant, zinc stearate, oleic acid, a mixture of stearic acid amide and ethylene bismuth stearic acid amide, lithium stearate and the like are preferable.

The above-mentioned iron powder, compound powder containing B,
A graphite powder, a lubricant and optionally added copper powder are mixed by a normal method such as a V blender with a mixed powder obtained by mixing a compound powder containing S by a normal method such as a V blender, and twice or more. A method of mixing separately may be used. Further, a segregation preventing treatment may be performed, and the compound powder containing B and the compound powder containing S may be mixed so as to adhere to the surface of the iron powder. This mixing method
It is better to do as follows.

To the above-mentioned iron powder, a fatty acid which is liquid at normal temperature is added and primary mixed, and then a compound powder containing B, a compound powder containing S, a graphite powder, and a copper powder and a metal soap added as necessary. Is added, and the temperature is raised during the secondary mixing or after the secondary mixing to produce a co-melt of the fatty acid and the metal soap, and then the mixture is cooled with the tertiary mixing, and the co-melt is cooled and fixed. The compound powder containing at least B and the compound powder containing S are adhered to the surface of the iron powder particles by the bonding force of the co-melt,
Further, at the time of cooling, it is preferable to add a metal soap or wax and to perform fourth mixing. By this segregation prevention treatment, it is possible to obtain an iron powder in which the compound powder containing B and the compound powder containing S are fixed to the surface of the iron powder. As a result, the amount of free graphite produced in the sintered body increases as compared with the simple mixing method using a V blender.

In the above steps, the compound powder containing B, the compound powder containing S, and the metal soap are added at the time of secondary mixing,
At the time of the fourth mixing, the above process may be partially modified so that graphite powder, copper powder and metal soap or wax to be added as necessary are added. Further, to the above-mentioned iron powder, a compound powder containing B, a compound powder containing S, graphite powder, and two or more kinds of waxes having melting points different from those of copper powder to be added as necessary are added, and the mixture is primary mixed. The temperature is increased after middle or primary mixing to produce a partial melt of the wax, then cooled while secondary mixing, and the partial melt is cooled and fixed, and the bonding force of the partial melt causes the surface of the iron powder particles to adhere to the surface. The compound powder containing at least B and the compound powder containing S may be fixed, and a metal soap or wax may be added at the time of cooling to perform tertiary mixing. Also,
In the above steps, compound powder containing B and compound powder containing S are added to the iron powder at the time of primary mixing, and two or more kinds of waxes having different melting points are added.
The above steps may be partially modified so that tertiary mixing with the addition of metal soap or wax is performed.

After the mixing, it is preferable to form a sintered body by pressing and molding to a predetermined green density and sintering.

[0032]

(Example 1) Atomized iron powder containing Mn shown in Table 1 and composed of a balance of Fe and unavoidable impurities was added to a compound powder containing B, a compound powder containing S, a graphite powder, a Cu powder, Lubricant,
A mixed powder was obtained by the following mixing methods 1 to 5. (Note that
Compound powder containing B, compound powder containing S, graphite powder and Cu
The compounding amount of the powder is shown by weight% with respect to the total amount of the compound powder containing iron powder and B, the compound powder containing S, the graphite powder and the Cu powder. ) Mixing method 1: These atomized iron powders were added as compound powders containing B,
Boric acid (H ₃ BO ₃ ), boron oxide (B ₂ O ₃ ),
One or more kinds of ammonium borate powder and hexagonal boron nitride (BN), and S powder in an amount shown in Table 1 as a compound powder containing S,
At least one of FeS powder and MnS powder, 1.5 wt% of graphite powder and Cu
One part by weight of zinc stearate was added to 2.0 parts by weight of the powder and 100 parts by weight of the total amount, and mixed with a V blender for 15 minutes to obtain a mixed powder.

Mixing method 2: To these atomized iron powders, 0.3 wt% of oleic acid was sprayed and uniformly mixed for 3 minutes. Then, the compound powder containing B and S in the amounts shown in Table 1 were mixed with graphite. 1.5 wt% of powder and 2.0 wt% of Cu powder, and 0.4 parts by weight of zinc stearate with respect to 100 parts by weight of the total of these powders, mix well, heat and mix at 110 ° C, and further mix at 85 ° C or less To obtain a mixed powder in which a compound containing graphite and B was fixed to iron powder particles with a eutectic binder of oleic acid and zinc stearate.

Further, 0.3 part by weight of zinc stearate was added to this mixed powder, based on 100 parts by weight of the total amount of the compound powder containing iron powder, oleic acid and B, graphite powder and copper powder, and uniformly mixed. . Mixing method 3: Atomized iron powder, compound powder containing B and compound powder containing S in the amounts shown in Table 1, graphite powder 1.5 wt%, and Cu powder 2.0 wt
%, And 0.4 wt% of a mixture of stearic acid amide and ethylene bisstearic acid amide, and thoroughly mixed.
The mixture was heated and mixed at 110 ° C., cooled to 85 ° C. or less while further mixing, and the compound containing graphite and B was fixed to the iron powder particles with a partial eutectic binder of stearic acid amide and ethylenebisstearic acid amide. It was a mixed powder.

Zinc stearate is added to the mixed powder, iron powder, a compound powder containing B, a compound powder containing S, a graphite powder, and a Cu powder.
0.3 parts by weight was added to the total amount of 100 parts by weight of the powder, the mixture of the stearic acid amide and the mixture of ethylene bisstearic acid amide, followed by uniform mixing. Mixing method 4: 0.3 wt% of oleic acid was spray-sprayed on the atomized iron powder and uniformly mixed for 3 minutes. Thereafter, the compound powder containing B, the compound powder containing S, and zinc stearate in the amounts shown in Table 1 were added to 0.4 parts by weight with respect to 100 parts by weight of the total amount of iron powder, oleic acid, graphite powder and Cu powder,
After adding and mixing well, the mixture was heated and mixed at 110 ° C., and cooled to 85 ° C. or less while further mixing, and the compound containing B was fixed to the iron powder particles with a eutectic binder of oleic acid and zinc stearate. It was a mixed powder.

In this mixed powder, 1.5 wt% of graphite powder, 2.0 wt% of Cu powder, zinc stearate, iron powder, compound powder containing B, compound powder containing S, graphite powder, Cu powder, olein 0.3 part by weight was added to the total amount of 100 parts by weight with the acid, and mixed uniformly. Mixing method 5: The amount of compound powder containing B and the amount of compound powder containing S and 0.4 wt% of a mixture of stearamide and ethylenebisstearic acid in the amounts shown in Table 1 were added to the atomized iron powder and mixed well. Thereafter, the mixture was heated and mixed at 110 ° C., and further cooled to 85 ° C. or less while further mixing to obtain a mixed powder in which the compound powder containing B was fixed with a partial eutectic binder of stearamide and ethylenebisstearic acid amide. .

In this mixed powder, 1.5 wt% of graphite powder and Cu
2.0wt% of powder, zinc stearate, iron powder, compound powder containing B, compound powder containing S, mixture of stearic acid amide and ethylenebisstearic acid amide, graphite powder and Cu powder 0.3 part by weight was added to 100 parts by weight, and the mixture was uniformly mixed. These mixed powders were molded under pressure to form molded bodies.

The compressibility of the mixed powder is 5 ton / cm ² .
It was molded into a cylindrical molded body of 10φ × 10 mm, and evaluated by its density. The higher the density, the better the compressibility. Free graphite amount and machinability pressurizes to a density 6.85 g / cm ^3, a cylindrical molded body, the molded body was sintered in 1130 ° C. × 20min in a nitrogen atmosphere containing 10 vol% hydrogen The evaluation was performed using the sintered body obtained by the sintering process.

The amount of free graphite in the obtained sintered body was determined by an infrared absorption method from a filtrate obtained by dissolving a part (sample) of the sintered body with nitric acid and filtering the residue through a glass filter. In addition, the machinability, using a cylindrical sintered body with an outer diameter of 60 mmφ and a height of 10 mm, a high-speed steel drill with a diameter of 2 mmφ at 10000 rpm, 0.
Rotate under the condition of 012mm / rev, make many holes in the test piece, average number of holes made before drill becomes impossible
(Average value of three drills) was obtained and evaluated by the numerical value.
The larger the value, the better the machinability.

Table 1 shows the results.

[0041]

[Table 1]

As shown in Table 1, the sinters (Nos. 1 to 5 and Nos. 10 to 13) produced from the iron-based mixed powder for powder metallurgy of the present invention have greatly improved machinability. On the other hand, in the sintered body No. 6 in which the compound powder containing S is not compounded and the compounding amount of the compound powder containing B exceeds the range of the present invention, the machinability is small but the compressibility is low. . In addition, there is no compound powder containing S, and the sintered body No. 8 has a low compounding amount of the compound powder containing B, the sintered body No. 9 has a low compounding amount of the compound powder containing S, and the Mn content is high. In the sintered body No. 7, the amount of free graphite was small and the machinability was reduced. Also, comparing the sintered powders No. 5, No. 10 to No. 13 with the same compounding amount of the compound powder containing B and different mixing methods,
The sintered bodies No. 10 to No. 13 which have been subjected to the segregation prevention
Compared with o.5, the amount of free graphite is larger and the machinability is excellent. (Example 2) An atomized iron powder as a base powder containing S and Mn shown in Table 2 was produced.

First, molten steel adjusted to a predetermined composition (the molten steel temperature
(Degree: 1630 ° C.) was atomized with water to obtain a powder. this
Have the powder been dried at 140 ° C for 60 min in a nitrogen atmosphere?
930 ° C x 20 min in a pure hydrogen atmosphere.
Was. After cooling, remove from the reduction furnace, pulverize, classify and
It was the base powder of iron powder. Carbonyl Ni
Powder, Mo trioxide powder, and Cu powder in proportions as shown in Table 2.
And annealed in hydrogen gas at 875 ° C for 60 min.
The alloy steel powder was diffused and attached to the surface. (Note that in Table 2,
The contents of Ni, Mo, and Cu are indicated by% by weight in the iron powder. ) These alloy steel powders were mixed with a compound powder containing B in the amount shown in Table 2.
The compound powder containing S, graphite powder and lubricant are shown below.
A mixed powder was obtained by mixing methods 1A to 5A. 1-5
Cu powder was mixed in the mixing method of 1A to 5A.
The method does not mix Cu powder. (The compound containing B
Powder, compound powder containing S and graphite powder are mixed with alloy steel powder.
Total amount of compound powder containing B, compound powder containing S, and graphite powder
% By weight. ) Mixing method 1A: These alloy steel powders were used as compound powders containing B as shown in Table 2.
The indicated amount of boric acid (H_ThreeBO _Three), Boron oxide (B_TwoO_Three), Boric acid
At least one of ammonium powder and hexagonal boron nitride (BN)
And the amount of S powder and Fe in the amount shown in Table 2 as compound powder containing S
At least one of S powder and MnS powder and 1.5 wt% of graphite powder
1 part by weight of zinc stearate per 100 parts by weight of
In addition, the mixture was mixed for 15 minutes with a V blender to obtain a mixed powder.

Mixing method 2A: 0.3 wt% of oleic acid was spray-sprayed onto these alloy steel powders and uniformly mixed for 3 minutes. Thereafter, the compound powder containing B in the amount shown in Table 2 and the S powder in the amount shown in Table 2 were mixed. , A graphite powder, 1.5 wt% of graphite powder, and 0.4 parts by weight of zinc stearate with respect to 100 parts by weight of the total amount, add them well, heat and mix at 110 ° C, and further mix at 85 ° C. The mixture was cooled below to obtain a mixed powder in which graphite and boric acid (H ₃ BO ₃ ) were fixed to iron powder particles with a eutectic binder of oleic acid and zinc stearate.

Further, 0.3 parts by weight of zinc stearate was added to this mixed powder with respect to 100 parts by weight of the total amount of the compound powder containing iron powder, oleic acid, B, the compound powder containing S, and the graphite powder. And homogeneously mixed. Mixing method 3A: In alloy steel powder, compound powder containing B in the amount shown in Table 2, compound powder containing S in the amount shown in Table 2, 1.5 wt% of graphite powder,
Add 0.4 wt% of a mixture of stearic acid amide and ethylenebisstearic acid amide and mix well, then 110 ° C
Then, the mixture was cooled to 85 ° C or less while mixing, and the graphite powder, the compound powder containing B and the compound powder containing S were partially eutecticized with stearamide and ethylenebisstearic acid amide. The mixed powder was fixed with a body binder.

To this mixed powder, zinc stearate was added in a total amount of 100 parts by weight of a mixture of iron powder, a compound powder containing B, a compound powder containing S, graphite powder, stearic acid amide, and ethylenebisstearic acid amide. Was added and uniformly mixed. Mixing method 4A: 0.3 wt% of oleic acid was spray-sprayed on the alloy steel powder.
After mixing uniformly, the compound powder containing B in the amount shown in Table 2, the compound powder containing S in the amount shown in Table 2, and zinc stearate are combined with iron powder, oleic acid, and graphite powder. 0 for 100 parts by weight.
Add 4 parts by weight, mix well, heat and mix at 110 ° C, cool to 85 ° C or less while mixing, and mix compound powder containing B and compound powder containing S in iron powder particles with oleic acid and stearic acid. The mixed powder was fixed with a zinc eutectic binder.

1.5 wt% of graphite powder, zinc stearate, and iron powder, a compound powder containing B, a compound powder containing S, a graphite powder, and oleic acid were added to the mixed powder in an amount of 100 parts by weight. And 0.3 part by weight and uniformly mixed. Mixing method 5A: 0.4 wt% of a mixture of alloy powder containing compound powder containing B in the amount shown in Table 2, compound powder containing S in the amount shown in Table 2, and stearamide and ethylenebisstearic acid amide
And mixed well by heating at 110 ° C., and further cooling to 85 ° C. or lower while further mixing. The compound powder containing B and the compound powder containing S are mixed with stearamide and ethylenebisstearic acid amide. The mixed powder was fixed with a partial eutectic binder.

To this mixed powder, 1.5 wt% of graphite powder, zinc stearate, a mixture of iron powder, stearic acid amide and ethylene bisstearic acid, a graphite powder, a compound powder containing B, and a compound containing S 0.3 part by weight was added to the total amount of 100 parts by weight with the powder, and the mixture was uniformly mixed. The mixing state of these mixed powders is conceptually shown in FIGS. 1 is a mixing method 1A, FIG. 2 is a mixing method 2A, and FIG.
A, FIG. 4 shows the mixing state when mixing by the mixing method 4A, and FIG. 5 shows the mixing state when mixing by the mixing method 5A.

These mixed powders were molded under pressure to obtain molded articles. For the amount of free graphite and machinability, the mixed powder described above has a density of 7.
0 g / cm ³ to form a columnar molded body, and a sintered body obtained by sintering at 1250 ° C. for 60 min in a nitrogen atmosphere containing 10% by volume of hydrogen was used. It was evaluated similarly. Furthermore, the possibility of straightening after sintering was investigated. The sintered body was heated at 850 ° C in an atmosphere with a carbon potential of 0.8%.
After heating for 30 minutes, bright quenching was performed in oil at 160 ° C., and the tensile strength after bright quenching was measured.

Table 2 shows the results.

[0051]

[Table 2]

From Table 2, it can be seen that the sintered bodies (No. 2-1 to No. 2-7, No. 2-14 to No. 2-1) produced from the iron-base mixed powder for powder metallurgy of the present invention.
In 7), the amount of free graphite was 0.5% or more, and the tool life, which is an index of machinability, was 130 pieces or more, and machinability was greatly improved.
In addition, the addition of Ni, Cu, and Mo increases the tensile strength after bright quenching to 90.
It shows a high strength of 0 MPa or more. In addition, straightening can be performed even with sintering. In addition, there was no compound powder containing S, and the compounded amount of compound powder containing B was small.
No.2-13, no compound powder containing B and no compound powder containing S
In o.2-8, the amount of free graphite was small and the machinability was reduced, and straightening was impossible. In addition, sintered body No. 2
No.-9, No.2-10 and No.2-11 had poor machinability and could not be corrected.

The amount of compound powder containing B and S
No. 2-1 and No. 2-14 to No. 2-17, which have the same compounding amount of the compound powder containing the same and different mixing methods, show that the sintered bodies No. 2-14 to No.2-17 is No.2
The amount of free graphite is larger than that of -1, and the machinability is excellent. (Example 3) An atomized iron powder containing Mn, Ni, and Mo shown in Table 3 and having a balance of Fe and unavoidable impurities was produced.

First, molten steel adjusted to a predetermined composition was atomized with water to obtain a powder, which was heated at 140 ° C. × 60 min in a nitrogen atmosphere.
930 ° C × 20min in pure hydrogen atmosphere after drying
After cooling, it was taken out of the reduction furnace, pulverized and classified to obtain atomized iron powder (alloy steel powder). To these alloy steel powders, a compound powder containing B in an amount shown in Table 3, a compound powder containing S in an amount shown in Table 3, graphite powder and a lubricant were mixed with mixing methods 1A to 5A shown in Example 2. A mixed powder was obtained by the same mixing method. These mixed powders were molded under pressure to form molded bodies. (Note that the compounding amounts of the compound powder containing B, the compound powder containing S, and the graphite powder are shown in terms of% by weight based on the total amount of the iron powder, the compound powder containing B, the compound powder containing S, and the graphite powder.) For the graphite content and machinability, the above mixed powder was obtained with a density of 7.0 g / c.
m ³ to form a columnar molded body, hydrogen 10
Evaluation was performed in the same manner as in Example 1 using a sintered body obtained by sintering at 1250 ° C. for 60 minutes in a nitrogen atmosphere containing volume%.

Further, in the same manner as in Example 2, the possibility of straightening after sintering and the tensile strength after bright quenching were measured. Table 3 shows the results.

[0056]

[Table 3]

From Table 3, it can be seen that the sintered bodies (No. 3-1 to No. 3-6, No. 3-12 to No. 3-1) manufactured from the iron-base mixed powder for powder metallurgy of the present invention.
In 5), the amount of free graphite was 0.80% or more, and the tool life, which is an index of machinability, was 120 pieces or more, and machinability was greatly improved. The addition of Ni and Mo also increased the tensile strength after bright quenching to 89.
It shows a high strength of 0 MPa or more. In addition, straightening can be performed as it is. Also, the sintered body No. 3-10 in which the compounding amount of the compound containing B was small, and there was no compounding of the compound powder containing B,
In the sintered compact No. 3-11 with a low compounding amount of the compound powder containing S and the sintered compact No. 3-7 with a high Mn content, the amount of free graphite was small and the machinability was remarkably reduced, so that straightening was impossible. became. In addition, in the sintered bodies No. 3-8 to No. 3-9 with a large amount of alloy addition, the machinability was lowered and the straightening was impossible.

Further, a comparison of the sintered bodies No. 3-2, No. 3-12 to No. 3-15 having the same blending amount and different mixing methods shows that the sintered bodies No. 3-12 to No.3-15 are N
o Compared with o.3-2, the amount of free graphite is large and the machinability is excellent. (Example 4) An atomized iron powder containing Mn shown in Table 4 and serving as a base powder was produced.

First, molten steel adjusted to a predetermined composition was atomized with water to obtain a powder, which was then heated at 140 ° C. for 60 minutes in a nitrogen atmosphere.
930 ° C × 20min in pure hydrogen atmosphere after drying
After cooling, the mixture was cooled, taken out of the reduction furnace, pulverized and classified to obtain an atomized iron powder base powder. An alloy obtained by mixing carbonyl Ni powder, Mo trioxide powder, and Cu powder with these base powders in the proportions shown in Table 4 and annealing in hydrogen gas at 875 ° C. for 60 minutes to adhere to the base powder surface by diffusion. Steel powder.
(Note that the contents of Ni, Cu, and Mo in Table 4 are shown in terms of% by weight in the iron powder.) In these alloy steel powders, a compound powder containing B in the amount shown in Table 4 and a compound powder containing B in the amount shown in Table 4 Compound powder containing S and graphite powder 1.5wt
% And the lubricant are mixed in the mixing method 1A to 5A shown in Example 2.
A mixed powder was obtained by the same mixing method as described above. (Note that the compounding amounts of the compound powder containing B, the compound powder containing S, and the graphite powder are indicated by weight% based on the total amount of the iron powder, the compound powder containing B, the compound powder containing S, and the graphite powder.) Was mixed under pressure to obtain a molded body.

The amount of free graphite and the sliding characteristics were determined by pressing the above mixed powder so as to have a density of 6.85 g / cm ³ to obtain a columnar molded body, which was heated to 1130 g in an RX gas (endthermic gas) atmosphere.
The evaluation was performed using a sintered body obtained by sintering at a temperature of 20 ° C. for 20 minutes. The amount of free graphite was evaluated in the same manner as in Example 1 using this sintered body. Further, for the sliding characteristics, a cylindrical test specimen having an inner diameter of 10 mmφ, an outer diameter of 20 mmφ, and a height of 8 mm was manufactured from the sintered body obtained by the above method, and an S45C shaft having a diameter of 10 mmφ was bored in the cylinder. With a clear run of 20 μm. Then, under dry conditions, the shaft is rotated at a peripheral speed of 100 m / min, and a wear resistance test is performed by gradually increasing the contact load from a low load, and the contact when the shaft and the inner wall of the cylinder are seized The load was defined as the sliding characteristics of the sintered body. The larger the contact load at the time of seizure, the better the sliding characteristics.

Table 4 shows the results.

[0062]

[Table 4]

From Table 4, it can be seen that the sintered body produced from the iron-based mixed powder for powder metallurgy of the present invention and the sintered body produced by the method of the present invention
(No.4-1 to No.4-6, No.4-10 to No.4-13) have a free graphite content of 1.1% or more and a contact load of 6 kgf / mm ²
It has high sliding characteristics as described above. Thus, when the amount of free graphite is 1% or more, the sliding characteristics are remarkably improved.
On the other hand, there was no compound powder containing S, and the compounded amount of compound powder containing B was small. No sintered powder No. 4-7, no compound powder containing B, and no compound powder containing S In the sintered body No. 4-8 with a small amount and the sintered body No. 4-9 with a high Mn amount, the amount of free graphite was small and the sliding characteristics were reduced. In addition, in the sintered bodies No. 4-10 to No. 4-13 subjected to the segregation prevention treatment, the amount of free graphite is increased and the sliding characteristics are improved.

[0064]

According to the present invention, the machinability and sliding characteristics of the sintered body are improved as compared with the conventional sintered body using iron powder and mixed powder. Further, if a mechanical part is manufactured from the sintered body according to the present invention, the dimensional accuracy of the mechanical part is increased, and the life of the mechanical part is extended,
Very useful in industry.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a mixed state of a mixed powder according to a mixing method 1A.

FIG. 2 is a conceptual diagram showing a mixed state of a mixed powder according to a mixing method 2A.

FIG. 3 is a conceptual diagram illustrating a mixed state of a mixed powder according to a mixing method 3A.

FIG. 4 is a conceptual diagram showing a mixed state of a mixed powder according to a mixing method 4A.

FIG. 5 is a conceptual diagram showing a mixed state of a mixed powder by a mixing method 5A.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kuniaki Ogura, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Inventor Masashi Fujinaga 1, Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works

Claims (6)

[Claims] An iron-based mixed powder for powder metallurgy, wherein iron powder, a compound powder containing B, a compound powder containing S, or graphite powder, or a mixture of graphite powder and a lubricant,
The compound powder containing B is made of one or more compound powders containing B, and the compound powder containing S is made of one or more compound powders containing S, and the compound powder containing B is mixed with the iron powder. And the compound powder containing B, the compound powder containing S, and further the graphite powder,
0.001 to 0.3% in terms of conversion, and the compound powder containing S is further added to the iron powder, the compound powder containing B, the compound powder containing S, and / or the graphite powder in terms of weight%. An iron-based mixed powder for powder metallurgy, characterized by being mixed at a conversion of 0.03 to 0.3%. 2. An iron base powder for powder metallurgy obtained by mixing iron powder, compound powder containing B, compound powder containing S, copper powder, or graphite powder, or graphite powder and a lubricant. The compound powder containing B is composed of one or more compound powders containing B, and the compound powder containing S is composed of one or more compound powders containing S. % By weight based on the total amount of the iron powder, the compound powder containing B, the compound powder containing S, the copper powder, and the graphite powder.
The compound powder containing S is 0.001 to 0.3% in terms of B, and the compound powder containing S is added in weight% with respect to the total amount of the iron powder, the compound powder containing B, the compound powder containing S, and further the graphite powder. , 0.03-0.3% in S conversion, and 4% of the copper powder
An iron-based mixed powder for powder metallurgy, which is mixed as follows. 3. The iron powder, in terms of% by weight, Mn: 0.05 to 0.40.
%. The iron-based mixed powder according to claim 1, wherein the powder is atomized iron powder containing Fe and unavoidable impurities. 4. The iron powder, in terms of% by weight, Mn: 0.05 to 0.40.
%, Ni: 0.5-7.0%, Mo: 0.05-6.0%
2. The iron-based mixed powder according to claim 1, wherein the powder is an atomized iron powder containing one or two selected from the group consisting of Fe and the unavoidable impurities. 5. The method according to claim 5, wherein the iron powder has a Mn content of 0.05 to 0.40% by weight.
% Of atomized iron powder consisting of the balance Fe and inevitable impurities. Ni: 0.5 to 7.0%, Cu: 0.5 to
2. The iron-based mixed powder according to claim 1, wherein one or more selected from 7.0% and Mo: 0.05 to 3.5% are partially alloyed iron powder. 6. The iron powder according to claim 1, wherein the iron powder is an iron powder having the surface containing the compound powder containing B and the compound powder containing S. Iron-based mixed powder.