DE2121481A1 - Sintered alloy and process for its manufacture - Google Patents

Description

PATEN .A itW ^ lTE

DR. E. WIEGAND DIPUING. W. NIEAAANN DR. AA. KÖHLER DIPL-ING. C. GERNHARDT 2121481

MÖNCHEN HAMBURG

PHONE-. 555474 8000 MÖNCHEN 15, TELEGRAMS: KARPATENT NUSSBAUMSTRASSE 10

April 30, 1971 W 40 475/71

Sumitomo Electric Industries, Ltd., Osaka (Japan)

Sintered alloy and process for its manufacture

The invention relates to sintered iron alloys in an excellent manner Heat resistance and wear resistance properties required for the manufacture of sliding parts or sliding bodies, used in particular for piston rings or valve disk rings for engines; it relates in particular to sintered alloys with iron, chromium, carbon and lead as components and the sliding parts or sliding bodies made from them. An essential one Feature of the sintered alloy according to the invention (liart alloy) is their self-lubricating property and consequently the sintered alloy according to the invention has more favorable ones Wear resistance properties to sliding motion even in unleaded gasoline.

So far, iron-carbon cast irons have been used as starting materials for sliding bodies, which have at least one alloy element, ζ. Β. Boron, phosphorus, nickel, manganese, silicon, copper and chromium, was added, or heat-resistant steels were used. , _{οββββ /} ^ ₁ ,, -

There has recently been a need for a sliding body with excellent heat resistance and sealing properties to improve the performance and durability of engines and various improvements have been made, to meet this need. For example, a sliding body made of the above-mentioned alloy was used, which plated with chrome or coated with molybdenum. In addition, a sliding body was also made using a metallurgical powder process and research and development of sintered alloy materials have also been carried out, those made of iron-copper-carbon as the main component and molybdenum, Manganese and silicon were produced as additives.

However, it soon became clear that all of the above-mentioned sliding bodies were only effective when used in a common gasoline. That is, a common gasoline becomes one Lead compound, for example tetraethyl lead, added as an anti-knock agent, but recently the contamination of the The atmosphere caused by the lead in the exhaust gas is a problem and there will be developments in unleaded gasoline and engines that do can be used along with unleaded gasoline.

The lead present in a gasoline currently in use Also serves as a lubricant in the engine, in particular, the lead adheres to a contact part of a valve and valve disc (Valve support) and thereby carries air preventing seizure of these parts and gives them wear resistance properties.-V.enn accordingly, the previously used sliding bodies are used in a unleaded gasoline increases the wear of the sliding bodies or sliding parts and it exists Accident risk for an automobile on a motorway in which worn sliding bodies are used. Therefore, the -

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Development of gasoline, in which the addition of lead is to be reduced or eliminated, with the development of sliding bodies excellent resistance and wear resistance properties and need self-lubricating properties.

The aim of the present invention is to provide a sintered alloy that can be used to manufacture sliding bodies with sufficient wear resistance even when used in a unleaded gasoline, excellent heat resistance properties and have favorable self-lubricating properties and in particular for the production of piston ring parts and valve seat ring parts can be used. Another object of the invention is to provide a method of manufacture specify the sintered alloy according to the invention.

The nature, details and advantages of the invention go below from the following detailed description, first considering the invention in general and then with reference to specific practical ones Examples illustrating preferred embodiments of the invention, and will be described with reference to other comparative and reference examples.

The sintered alloy of the present invention is prepared by mixing carbon powder, iron powder and lead powder with an Fe-Cr alloy so that a predetermined mixing ratio thereof is obtained, and then the mixture thus obtained is sintered in a gas atmosphere. The ratio of the individual components is such that 0.5 to 40% of Cr, O ₁ I to 3.0% of C, 0.2 to 20% of Pb and the remainder of Fe, each based on weight . In addition, if better heat resistance of the alloy is desired, a small amount of at least one element selected from Ni, Mo, Si, Kn and Cu can be added to the above-described mixture, and in this case any amount within

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the following range specified in each case are added, d. H. Ni from 0.5 to 20%, Mo from 0.1 to 3.5%, Si from 0.05 to 3.0%, Mn from 0.05 to 5.0% and Cu from 1.0 to 30%. aside from that can improve the mechanical and physical properties of the alloy by adding a small amount of an element Co, W, Ta, Ti, V or Al adjusted to the above mixture or be modified.

The Cr component is added in the form of ferrochrome powder and with the other components or the other alloy powder mixed and especially when the Cr component is in shape

ΙΠΙΚΘΪΙ

of Fe-Cr or Fe-Cr-Ni sigma phase mother alloy / is added, there is an advantage that a sintered body can be easily manufactured; H. it can easily be a sintered body with a high density due to only one compression deformation and sintering process step.

It should be noted that Pb is not just a mixture of Fe-Cr alloy powders, Fe powder and C powder before sintering the same can be introduced, but that it can also be impregnated into one by sintering the mixture described above produced sintered body can be introduced into this. Ni and Mo become the mixture to be sintered in Form of sigma phase mother alloy powder added. In addition, other additives or impurities can also be used above may be included in the mixture, provided that the addition does not deviate from the objectives of the invention.

Each component in the alloy is described in more detail below.

The carbon belongs to an essential element that the finished product gives mechanical strength and wear resistance and if the carbon is in an amount of

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less than 0.51 is added, no noticeable improvements can be made mechanical strength and wear resistance can also be observed in the case of the addition of less than 0.11 carbon no improvement in the finished product is expected. On the other hand, im If more than 2.0% carbon is added, there is little tendency for the alloy to become brittle and if the Carbon is added in an amount greater than 3.0%, this tendency becomes quite evident. In the event that the Sintered alloy according to the invention, in particular for piston ring parts is used in various sliding bodies, the carbon is added within a range of 1.5 to 2.0% and in the case that the alloy is used for valve seat ring parts, the carbon is used in an amount preferably added within a range of 0.1 to 3.0%.

The chromium combines with the carbon in the alloy to form carbide and part of it forms a solid solution with the iron, which increases the alloy's heat resistance and is also effective in preventing oxidation and corrosion by gases because a permanent and thin oxide film is formed on the surface of the alloy. '.Venn the chromium is added in an amount of less than 1%, so the contribution of this addition, in view of improving the oxidation resistance and the iiärmebestandigkeit _o ering and if the chromium in an amount of less than G, ^5? «Is added, the sintered alloy obtained is unsuitable for piston ring parts. On the other hand, when the chromium is added in an amount of more than 10%, there appears to be a tendency to lower the toughness of the alloy, and in the case of more than 40% of the chromium, a molded article with sufficient strength cannot be obtained because of the compressibility of the powders is disturbed. When the sintered according to the invention

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Alloy used for piston ring parts x ^ ird, the chrome is used in is added in an amount within the range of 0.5 to 10.0%, and in the case of using it for valve seat ring parts, a Range from 1 to 40% suitable.

The lead is used to improve the mechanical workability of the alloy when it is processed into each specific sliding body with a certain shape. When a sliding element is inserted into an engine and slides in unleaded gasoline, the lead dispersed in the matrix of an iron-chromium-carbon alloy exits to the sliding surface, forming a thin film of lubricant, which prevents the lead from seizing up with the built-in cylinder , smooths the sliding of the ring and improves the wear resistance of the sliding body. In addition, when small pieces of dust are contained in the gasoline and air mixture and held on a sliding surface, the pieces of dust are embedded in the soft lead already on the sliding surface, causing abrasion of the piston ring and the cylinder liner the dust grain is reduced. When the lead is added in an amount of less than 0.2%, the above-mentioned effects or advantages of the lead are small, while when the lead is added in an amount of more than 10.0%, there is a tendency that the. the mechanical strength of the alloy gradually decreases, and furthermore, if the amount of lead added is more than 20%, the alloy itself becomes correspondingly brittle, which is undesirable. When the inventive sintered alloy is used for piston ring parts, the amount of lead should be within a range of 0.5 to 10%, and when used for piston bearing ring parts, a range of 0.2 to 20 ^f s is suitable.

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The following are the conditions for compression deformation Compression deformation) and sintering of the mixture to be sintered described in more detail.

Preferably, for sintering, the mixture is compression-molded under a pressure of 1.0 to 10 t / cm ^{2 and} sintered in a non-oxidizing gas atmosphere at a temperature of 1150 to 135O.degree. When the sintering temperature is below 1150 ⁰ C, the diffusion of Cr is insufficient and it can not be expected improvement of wear resistance, while on the other hand, if the temperature is above 135 ° ⁰ C, the dispersion of Pb is remarkably, and thereby the lubricating effect becomes poor. In addition, when the obtained sintered body is cold or hot forged, the following advantages are obtained:

1. The Pb contained in the sintered alloy or the Pb compound contained therein come to the surface the same, as a result of which the lubricating effect of the alloy becomes better;

2. The distribution of the pores of the sintered body and thus the degree of Pb leakage can also be controlled will;

3. The leaked Pb accumulates on the surface part of the sintered body and, as a result, becomes the The lubricating effect of the sintered alloy in unleaded gasoline is very good.

For the forging conditions mentioned above, a range of 3.0 to 20 t / cm is suitable and if the pressure is less than 3.0 t cm, the effect is on increasing the density of the

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sintered alloy is small and, on the other hand, when the pressure is more than 20 t / cm *, Pb is forced out of the alloy and this is a cause of the deterioration in the lubricating property of the sintered alloy.

The sintered alloy according to the invention has such a microscopic structure or texture that the lead with the excellent self-lubricating properties in an iron-chromium-carbon alloy matrix with a high V / heat resistance and good wear resistance and mechanical properties. Therefore, if necessary, the To further improve heat resistance and wear resistance depending on the operating conditions of the engine the elements Ni, Mo, Si, Mn, Cu, etc. are added to the above-mentioned alloy. When the sintered alloy of the present invention has the above-mentioned component and constituent ranges, the obtained alloy has a satisfactory one mechanical strength and, from this, sliding bodies with a higher heat resistance can be obtained in an economical manner and better wear resistance as well as more favorable self-lubricating properties can be produced than this is the case with conventional cast sliding bodies and sliding bodies made of a sintered alloy. If, in addition, from the invention Alloy-made sliding bodies or sliding parts can be used in a gasoline to which no tetraethyl lead is added has been, or are used in other motor fuels, the sliding bodies according to the invention have more favorable effects or advantages over one of the above-mentioned conventional sliding bodies.

As already mentioned above, the sliding bodies according to the invention have significantly better properties than piston rings and bearing rings in unleaded gasoline than those made from a special

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cast iron and heat-resistant steel, previously used Sliding body. In addition, the wear resistance of the sliding bodies according to the invention is also better than that a sliding body made from a simply sintered chrome steel.

It should also be noted that the sintered according to the invention Alloy of course not only for piston rings and bearing rings, but also for other sliding bodies and wear-resistant ones Parts can be used that will be used in an environment in which there are corrosion and oxidation problems high temperature occur, similar to the piston rings and bearing rings described above.

The following examples show specific preferred embodiments of the invention are described are intended to explain the nature and utility of the invention in more detail. The one in it However, the results given are only for illustration and the invention is by no means restricted thereto.

example 1

A mixture of Fe-5 $ Cr-H C, which consists of 40% by weight

It consisted of a Cr-Fe sigma phase mother alloy / powder (-0.044 mm (-325 mesh)), Fe powder (-0.15 mm (-100 mesh)) and carbon powder (-0.044 mm (-325 mesh)) as well as another mixture of a composition of Fc-5% Cr-1 ^? o C-21 Pb obtained by further adding a lead powder (-0.15 mm (-100 mesh)) to the former mixture. These mixtures were each compression molded in a metal mold under a pressure of 6 t / cm to produce molded articles.

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- το -

When these molded articles were heated and sintered in a highly pure hydrogen atmosphere at a temperature of 125O ⁰ C for 1 hour, densification of the structures of the molded articles occurred and sintered bodies having a high density were obtained, respectively.

In the following table I are the essential characteristics or Data of the two shaped objects and their respective compositions specified.

composition

Table I.

Specific specific

Weight of the weight of the

shaped sintered HV

Body body hardness

Fe-SICr-UC

6.20

Fe-5ICr-1IC-2 $ Pb 6.30

7.40 400 7.50 380

Rockwell hardness

HRC 35 HRC 30

Example 2

A mixture of Fe-5SCr-2.2INi-O, 43% Mo-1IC, the by mixing Fe-46 wt. S Cr-20 wt. l Ni-4 wt. IMo sigma phase mother alloy powder (-0.044 mm (-325 mesh)), Fe powder (-0.15 mm (-100 mesh}) and carbon powder (-0.044 mm (-325 mesh)), as well as another mixture of the composition Fe-SSCr-2,2INi-O, 43IMo-1% C-2 £ Pb, obtained by further adding lead powder (-0.15 mm (-100 mesh)) to the former mixture. These mixtures were each compressed in a metal mold under a pressure of 6 t / cm to produce molded articles. The obtained molded articles were in a

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- ii -

high-purity hydrogen atomosphere at a temperature of 12SO ⁰ C for 1 hour each heated and sintered. The following Table II gives the essential properties or data of the two molded articles and their compositions.

Table II

setting together

Specific specific weight of the weight of the molded body

Fe-5 * Cr-2.2SNi-0.43SMo-HC 6.25

Fe-5 * Cr-2.2 INi-0.43 * Mo-UC-2 * Pb 6.35

sintered
Body HV-
hardness Rockwell
hardness 7.45 450 HRC 40 7.50 430 HRC 35

Example 3

In an engine, bearing rings, which are derived from the examples 1 and 2 obtained sintered bodies had been produced, and other bearing rings made of a Ni-Cr cast iron or shell cast steel (SKD 1) were made

and which are commonly used are built-in. The engines were subjected to 200 hours of stationary tests and the Weights of the seat rings were determined before and after the tests. The heat resistance and wear resistance properties these bearing rings (valve disk rings) were determined after the test on the basis of the respective weight loss determined in percent. The results of these tests are summarized in the following Table III.

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Day 1 1 e III

Inlet outlet

Material side side

Fe-SICr-IIC 0.51 1.3%

Fe-SICr-UC + ZlPb * 0.2 1.0

Fe-5ICr-2.2INi-0.43IMo-UC 0.5 1.2

Fe-SiCr- 2,2SNi-O, 43lMo-1IC .

+ 2IPb 0.2 0.8

Ni-Cr cast iron 1 »0 4.0

Shell cast steel (1st class) 1.0 2.5

Sintered alloy according to the invention.

Example 4

A mixture of the composition Fe-5 $ Cr-1 «C-2-oPb was produced, by mixing a sigma phase mother alloy powder (Fe-40 wt. ICr) (-0.044 mm (-325 mesh)), iron powder (-0.15 mm (-100 mesh)), carbon powder (-0.044 mm (-325 mesh)) and lead powder (-0.05 mm (-280 mesh)). The received The mixture was compression-molded into a molded article in a metal mold under a pressure of 6 t / cm. Of the The molded article obtained was placed in a highly pure hydrogen atom heated at a temperature of 125O ° C for 1 hour and sintered.

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Example 5

A powdery mixture of a composition of Fe-2ICr-1.5% C-4lPb was prepared by mixing ferrochrome powder (Fe-63 wt. I Cr) (-0.044 mm (-325 mesh)), iron powder (-0, 15 mm (-100 mesh)), carbon powder (-0.044 mm (-325 mesh)) and lead powder (-0.05 mm (-280 mesh)) each mechanically mixed with each other. After the resulting powdery mixture was compression- ^{molded under a pressure of 5 t / cm 2} , the molded article obtained was under the. sintered under the same conditions as in Example 4. .

Example 6

A sigma phase mother alloy powder (Fe-46 wt-4 Cr-20 wt-I Ni-4 wt% Mo) (-0.044 mm (-325 mesh)), iron powder (-0.15 mm (-100 mesh)) , Carbon powder (-0.044 mm (-325 mesh)) and lead powder (-0.05 mm (-280 mesh)) were mixed in a mixing ratio of Fe-5% Cr-2.2% Ni-0.43Ulo-6! Pb -0.5 * C mixed together. The obtained mixture was compression molded under a pressure of 5 t / cm, and then the molded article thus obtained was ^{sintered at a temperature of 1200 °} C. for 1 hour in an ammonia cracking gas.

For comparison with the sintered alloys of Examples 4 to 6 inclusive, common cast alloys and sintered alloys were used Alloys tested for their various characteristics and their wear resistance properties. The test conditions were that each piston ring made from each alloy was inserted into a conventional one The engine was installed and that the engine was at a standstill at one number of revolutions of 4000 rpm using normal gasoline

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(containing tetraethyl lead) tested at full throttle for 200 hours became. After the test, the wear of each piston ring material was determined, with the wear being expressed by its tapped size of the outer diameter of the ring and in this case existed in connection with the The above piston ring used cast iron cylinders.

In addition, tests similar to the above were carried out, in which regular gasoline was replaced by unleaded gasoline and ■ * the wear of each piston ring was determined. The one with it The results obtained are summarized in Table IV below.

Table IV

alloy composition
(Wt%) Tensile strength
speed in
kg / mm * UV
hardness Tested
tes
Petrol. loss
by Ver
wear μ / Example 4 Cr 5%, C 11
Pb 2%, balance Fe 80 350 without lead 13th Example 5 Cr 2%, C 1.5%
Pb 4%, remainder Fe 60 250 normal 10 Example 6 Cr 5%, Ni 2.2%,
Mo 0.431, Pb 6%,
C 0.5% 100 400 without
lead 8th F with chrome
plated
Cast iron Si 2.5%, C 3.2%,
Pb 0.3%, balance Fe 35 280 normal 18th ti If 35 280 without lead 50 sintered
material Cu 3.0%, C 1.5%,
Remainder Fe 37 200 without lead 55

alloy according to the invention.

common alloy.

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As can be seen from the table above, the invention sintered alloys have a higher mechanical strength and hardness than the usual alloys and the The alloy according to the invention is also important in terms of its wear resistance property Superior to conventional alloys in both regular and unleaded gasoline.

Example 7

There was a mixture of a composition of Fe-SiCr-HC obtained by mixing 40% by weight of Cr-Fe sigma phase mother alloy powder (-0.044 am (-325 mesh)), Fe powder and carbon powder, and another mixture of the composition Fe-5ICr-14C-2? IPb obtained by further admixing lead powder (-0.05 mm (-280 mesh)) to the mixture prepared first. These mixtures were each compression molded under a pressure of 6 t / cm to produce molded articles. The molded articles were heated in a high purity hydrogen atmosphere at a temperature of 125O ⁰ C for 1 hour * and sintered to produce sintered bodies with an apparent specific gravity of 6.5 g / cm * and 6.55 g / cm. Both sintered chrome steels were heated in a nitrogen atmosphere at a temperature of 900 ° C. and each compressed in a metal mold under a pressure of 12 t / cm. The characteristics of these two sintered bodies are given in Table V below.

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Table V

Fe-5 SCr-HC composition

(I) Fe-SICr-HC

Specific weight of the sintered body (g / cm " ⁵ )

6.50 specific
Spawn of
hot compressed body
Tg / cm ⁵ )

7.20

(II) Fe-SiCr-HC-2IPb 6.55 7.40

Seizing in the metal mold ⁺

after shaping or forging 2-3 bodies seizure occurred

it could be continuously formed or forged v / earth

(I) Comparative example (II) according to the invention

Seizure in wetall form: This indicates how many forged body without seizing to the surface of the Metal mold could be obtained if using a forged metal mold a bowl guj.schniieden (the forging) was carried out.

As is apparent from the above table, in the sintered body of the composition (II) containing Pb, the "Pb or Pb compound" leaked out on the surface thereof at the time of arm compression, and a lubricating film was formed on the surface of the sintered body Accordingly, the anti-friction effect of the sintered body of the composition (II) against a metal mold " ^{5 was} remarkably good and

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it also increased the specific gravity of the compressed body the composition (II) due to the pressure during the compression of the same is significantly more than that of the sintered one Body of composition (I). It also occurred in the compressed Body of the composition (II) did not seize to the metal mold and it could therefore be continuously compressed will.

Then abrasion tests were carried out with your sintered in unleaded gasoline Body of the above composition (II) carried out and the results obtained were as follows:

Test conditions: it became an internal combustion engine, two

Cylinder, 360 cm ^3, 7500 rpm using 4/4;

Gasoline used: unleaded gasoline (lead content 0.002 g /

3.78 1 (gallon)) with an octane rating of 90.

Result: The abrasion loss was 0.15 mm over a test duration of 70 hours.

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Claims (1)

Claims 1. Sintered alloy, characterized in that it contains iron, chromium, carbon and lead and a structure in which the lead is dispersed in the Fe-Cr-C alloy matrix is. 2. Sintered alloy according to claim 1, characterized in that that the mixing ratio is such that chromium 0.5 to 40% by weight, carbon 0.1 to 3.0% by weight, lead 0.2 to 20% by weight make up and the rest is iron. 3. Sintered alloy according to claim 1, characterized in that that they also contain a small amount of a metal powder composed of at least one of the elements Ni, Mo, Si, Mn, Cu, Co, Ίί, Ta, Contains Ti, V and Al. 4. Sintered alloy according to claim 1, characterized in that it has been produced in such a way that Fe powder, Pb powder and C powder with an Fe-Cr or Fe-Cr-Ni system sigma phase mother alloy powder have been mixed to form a mixture that has been compression molded and in which the molded body obtained was sintered. fj. Sintered alloy according to Claim 1, characterized in that the Lo. ie is run j in the manner been DAT Fe "powders, I ¹ L-FuIVc r and C-PuIvor nit an Fe-Cr or Fe-Cr-Ni-Systu; u ~ SIgHIa were hasenniutterlegierun ₁ ^ ^ spulver emischt to form a mixture which was cor / ipressJLonsverfürr.it that the molded body obtained was sintered and that 109886 / in 1 BATH 2121-81 the sintered body was subjected to a forging treatment. 6. Slider, characterized in that it consists of a sintered Alloy is made that contains iron, chromium, carbon and lead and has a structure in which the lead is dispersed in an Fc-Cr-C alloy matrix. 7. Sliding part, characterized in that it consists of a sintered Alloy was made that contains iron, chromium, carbon and lead and has a structure in which the lead is dispersed in an Fe-Cr-C alloy matrix. 8. Piston ring part, characterized in that it consists of a sintered Alloy was produced which contains 0.5 to 10% by weight of chromium, 0.5 to 2.0% by weight of carbon, 0.5 to 10.0% by weight of lead, The remainder contains iron and has a structure in which the lead is dispersed in the Fe-Cr-C alloy matrix. 9. valve support ring part (valve disk ring part), characterized in that that it was made of a sintered alloy containing 1 to 40% by weight of chromium, 0.1 to 3% by weight Contains carbon, 0.2 to 20% by weight lead, the remainder iron and has a structure in which the lead in the Fe-Cr-C alloy i.iatrix is dispersed. 10. Process for making a sintered alloy riit a structure in which the lead is dispersed in an Fe-Cr-C alloy matrix, characterized in that Fe-PuI-ver, Pb powder and C powder with an Fe-Cr or Fe-Cr-Ni system alloy powder be mixed to form a 109886/1111 . 212H81 Mixture that the mixture is deformed under pressure and that the molded article obtained is sintered. 11. The method according to claim 10, characterized in that as Fe-Cr or Fe-Cr-Ni system alloy, a sigma phase mother alloy is used. 12. The method according to claim 10, characterized in that within a
is sintered within a temperature range of 1150 to 135O ° C 13. A method of making a sintered alloy having a structure in which the lead is in an Fe-Cr-C alloy matrix is dispersed, characterized in that Fe powder, Pb powder and C powder with an Fe-Cr or Fe-Cr-Ni system alloy powder are mixed to form a mixture that the mixture is deformed under pressure that the one obtained Molded body is sintered and that the sintered body is then subjected to a forging treatment. 14. The method according to claim 13, characterized in that the forging treatment under a pressure of 3.0 to 20 t / cm ^ fe is carried out. 15. The method according to claim 13, characterized in that it the forging treatment is hot forging. 16. The method according to claim 13, characterized in that it the forging treatment is cold forging. 109886/1111 212U81 17. A method for producing a sliding part, characterized in that that Fe powder, Pb powder and C powder with one Fe-Cr or Fe-Cr-Ni system alloy powder to form a mixture are mixed that the mixture is brought into the appropriate shape under pressure and that the obtained Molded body is sintered. 109886/1111