KR101858795B1

KR101858795B1 - Light sintered body having high strength and toughness and manufacturing method thereof

Info

Publication number: KR101858795B1
Application number: KR1020150178941A
Authority: KR
Inventors: 구진모
Original assignee: 주식회사 포스코
Priority date: 2015-12-15
Filing date: 2015-12-15
Publication date: 2018-05-18
Also published as: KR20170071634A

Abstract

The present invention relates to a lightweight sintered body excellent in strength and toughness, and a method of manufacturing the same.
The light sintered body according to one aspect of the present invention is a sintered body obtained by sintering an Fe-Ni powder and an Al powder. The sintered body has a total composition of 5.0 to 15% of Al, 5.0 to 10.0% of Ni, It may contain impurities.

Description

TECHNICAL FIELD [0001] The present invention relates to a lightweight sintered body having excellent strength and toughness, and a method of manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a lightweight sintered body excellent in strength and toughness, and a method of manufacturing the same.

Reducing the weight of components used in automobiles is essential for fuel consumption reduction and environmental conservation by improving fuel efficiency. To this end, techniques for manufacturing lightweight parts in various ways have been proposed.

One of them has been proposed a technique for manufacturing a low specific gravity component by adding a large amount of aluminum having a low specific gravity to a conventional steel.

However, in order to add a large amount of Al to automotive steel for light weight, it is necessary to add Al to the molten metal by casting. In the cooling process for casting, fine segregation occurs due to difference in melting point between Fe and Al. As a result, there is a difference in the content of additive elements depending on the position of the casting structure, thereby deteriorating the hot rolling property and eventually causing plate breakage in the production of the plate, which makes the production of the plate material very difficult.

Also, in the case of a steel having a high Al content, the BCC and the regular phase (B2, DO3) are stabilized at room temperature, and the phase-to-phase conformity at room temperature is lowered, thereby deteriorating ductility. Due to such a phenomenon, it is very difficult to obtain a cold-rolled sheet having a desired thickness in the process of cold-pressing a hot rolled sheet by securing a hot rolled sheet by partially improving the hot rolling property by taking much effort to control a high- Rolled to control the regular phase through hot rolling, etc., but it is very difficult to obtain a final product applicable to automobiles.

Therefore, in order to reduce the weight of automobile parts, it is necessary to increase the Al content in the steel. However, due to the problems of hot-pressing and room-temperature formability, there is a limit to the weight reduction by increasing the Al content. In addition, There is a problem in that it is difficult to produce a component having a large volume.

In order to avoid the problem of manufacturing lightweight parts through production and processing in the form of plate, a method of producing lightweight parts through casting and forging can be considered. However, when a product is manufactured by casting or forging, the process ratio is increased according to the production and use of the consumable form, and further processing cost is required to adjust the dimension in the form of the final part. In addition, There is a problem in that it decreases.

According to one aspect of the present invention, a new type of material is provided that can satisfy both the weight reduction of the parts and the processability.

A further aspect of the present invention provides a novel method for efficiently producing the above-mentioned material.

The object of the present invention is not limited to the above description. Those skilled in the art will appreciate that there is no difficulty in understanding the further task of the present invention from the overall content of the present disclosure.

A light-weight sintered body according to one aspect of the present invention is a sintered body obtained by sintering Fe-Ni powder, Al powder and C powder, wherein the total composition comprises 5.0 to 15% of Al, 5.0 to 10.0% 0.5 to 1.0%, the balance Fe and other unavoidable impurities.

A method of manufacturing a lightweight sintered body according to still another aspect of the present invention is characterized in that the Fe-Ni powder, the Al powder and the C powder are mixed in a weight ratio of Al: 5.0-15%, Ni: 5.0-10.0%, C: 0.5-1.0% The balance Fe, and other unavoidable impurities; Milling the mixture to obtain a green compact; And heating the mixture at a high temperature to obtain a sintered body.

As described above, the sintered body produced according to the present invention is excellent in toughness and workability by using Fe-Ni powder forming an austenite structure as a base powder, and a high strength is obtained due to the powders added together And is suitable for use as a material in fields requiring high strength and high processing.

1 is a graph showing particle size distribution of Fe base powder used in the present invention.
FIG. 2 is a graph comparing the lightening ratios of the sintered bodies manufactured according to an embodiment of the present invention with those of the same composition.
3 is a micrograph of a cross section of a sintered body manufactured by Inventive Example 1 of the present invention by transmission electron microscopy (TEM).

Hereinafter, the present invention will be described in detail.

The inventors of the present invention have conducted intensive researches to produce lightweight parts having excellent strength and toughness. As a result, it is possible to prevent segregation in the case where the above-mentioned parts are produced by sintering after mixing and pulverizing powders containing different elements But also strength and toughness can be ensured, leading to the present invention.

That is, one aspect of the present invention provides a lightweight sintered body unlike a conventional lightweight alloy. Since the sintered body is not completely dissolved by mutual solubility of the constituent powders constituting the sintered body, but the powder is locally melted or diffused at the boundary while maintaining the characteristics of the powder, The problem of technology can be solved.

Further, in the present invention, the most commonly contained known powder is an Fe-Ni-based powder so that the powder becomes a composite structure of austenite and ferrite, thereby securing toughness of the entire sintered body.

In addition, when powdering and sintering are performed by mixing aluminum powder together with the base powder, BCC or regular phases (B2, DO3) are generated at the boundary between the base powder and the aluminum powder, and these disperse and strengthen the entire sintered body . In addition, the C powder included in the C powder serves to improve the strength of the sintered body by forming phases such as Fe3AlC.

Further, in addition to the powders described above, the present invention can further control the strength, impact characteristics, and the like of the sintered body by further adding powder such as P in accordance with the overall composition of the target sintered body. Hereinafter, the characteristics of each powder to be introduced in the present invention will be described in detail. It should be noted that the content of each component described below is based on weight unless otherwise specified.

Fe-Ni powder

In the present invention, the Fe-Ni powder is used as a base powder. That is, since the present invention replaces the conventional demand for lightweight steel for automobiles, Fe-Ni powder containing Fe is used as a base powder. At this time, the contained Ni plays a role of stabilizing the austenite, so the Fe-Ni powder of the present invention has a structure in which austenite and ferrite are mixed. Powders containing austenite can have high impact properties. In order to obtain such an effect, it is preferable that Ni in the Fe-Ni powder is contained at not less than 5.5%. However, if the Ni content is excessive, the Ni content in the entire sintered body is increased, and the Al content of the sintered body reacts with Al contained in the Al powder to form a regular phase such as Ni3Al, which may lower the toughness. Therefore, the upper limit of the Ni content in the powder is 11.0 %. According to one embodiment of the present invention, the austenite structure of the Fe-Ni powder may include 30 to 80% by area.

Al powder

In the present invention, Al powder means that Al is contained in an amount of 99.5% or more. Since the specific gravity of pure Al is 2.7 and is only 35% of iron, when the Al powder is included in the sintered body, the specific gravity of the sintered body is greatly reduced, thereby making it possible to manufacture the lightweight sintered body. Also, according to the study results of the present inventors, the Al powder reacts with the iron atoms of the Fe-Al powder to form a BCC or regular phase (B2, DO3), wherein the formed rule phase is locally formed only at the interface of the two powders, As a whole, since the interface of each powder is uniformly dispersed, it eventually serves to disperse and strengthen the sintered body. Therefore, it plays a role of greatly improving the strength of the light-weight sintered body of the present invention.

C powder

In the present invention, the C powder combines with Fe of the base powder and Al of the Al powder to form a phase such as Fe3AlC, thereby improving the strength. That is, the formed phase can act to improve the strength through dispersion strengthening in the sintered body, and therefore can be preferably included in the sintered body of the present invention.

In the present invention, powder of an element having a strengthening effect such as P powder may be additionally included, if necessary, in addition to the above-mentioned powder.

In the present invention, Ni powder may be separately prepared and mixed so as to satisfy the entire composition of a sintered body to be described later. That is, it may not be easy to prepare all kinds of powders according to the entire composition of the sintered body due to the characteristics of the powder metallurgy. Therefore, a small amount of Ni powder may be added to the sintered body composition to control the overall sintered body composition.

FIG. 1 shows one example of particle size distribution of Fe-Ni powder according to one embodiment of the present invention. In Fig. 2, D _50, which means the median value of the Fe-Ni powder particle size, is shown to be 89 탆. If the particle size of the powder is too large, it is difficult to obtain a uniform component distribution as a whole, and there may be a side effect such that one powder forms a segregation. However, if the size of the powder is too small, a homogeneous composition may be obtained as a whole. However, the sintering temperature differs from that of the Fe-Ni powder and the Al powder, Likewise, there may be a problem of degradation in toughness due to the rule. Therefore, the size (D ₅₀ ) of the Fe-Ni powder can be limited to 70 to 100 탆. Particularly, it is advantageous that the powder of 99% or more (on the number basis) of the whole powders has a particle size of 250 mu m or less so that powder having an excessive particle size is not included.

In addition, a D ₅₀ median of the particle size of each powder other than the Fe-Ni powders (previously equivalent diameter standard) can be limited to 40 ~ 60㎛. The particle size of 99% or more of powder on the number basis may be 100 탆 or less. That is, when the particle size of the powder is too large, it is difficult to obtain a uniform component distribution as a whole, and the size of the powder can be limited to 100 μm or less since a single powder may have side effects such as segregation. However, if the size of the powder is too small, a uniform composition as a whole may be obtained, but the degree of melting and mixing diffuses compared to the size of the Al powder at the sintering temperature, resulting in too much BCC or regularity A problem of degradation in toughness may occur. Therefore, the size of the Al powder can be limited to 1 mu m or more. However, in the case of C powder, P powder or Ni powder, it is added for the purpose of strengthening the base powder by being dissolved in the base powder. Therefore, the upper limit of the particle size of the C powder, the P powder and the Ni powder is limited as described above, but the lower limit is not particularly limited. However, according to one embodiment, the lower limit of the particle size of the C powder, the P powder, and the Ni powder may be set to 1 탆 in consideration of the particle size of the industrially produced powder. Further, since the Fe-Ni powder (base powder) and the Al powder are uniformly dispersed, a uniformly dispersed precipitate phase can be obtained, so that the span of the particle size of the powder {(D ₉₀ -D ₁₀ ) / D ₅₀ } More preferably 3.0 or less.

The sintered body of the present invention containing the powder described above is used in an amount of 5.0 to 15.0% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, balance of Fe and other inevitable It may have a total composition including impurities. In the present invention, the term " whole composition " means a composition obtained by analyzing the composition of a sintered body in a bulk unit rather than a powder unit. For the analysis of the composition of the sintered body, cylindrical specimens with a diameter of 10 mm and a height of 10 mm can be used to ensure the objectivity of analysis. Hereinafter, the reasons for determining the content of each element will be described.

Al: 5.0 to 15.0%

As described above, Al is an element necessary for lightening the sintered body. In addition, it is combined with Fe to form a regular phase of B2 / DO3 and BCC, thereby obtaining an effect of increasing the strength by strengthening dispersion. Therefore, in the present invention, Al is contained in an amount of 5.0% or more. However, if the content of Al is excessively high, a rule phase B2 / DO3 is excessively formed, so that a regular phase is formed within the Fe-Ni base powder, and the ductility is reduced. To prevent this, the upper limit of the Al content is limited to 15.0% .

Ni: 5.0 to 10.0%

Ni is added for the purpose of improving the impact property. To achieve this purpose, the Ni content may be 5.0% or more. Also, in one embodiment, the Ni may diffuse into the base powder and serve to make the matrix structure a complex structure of austenite and ferrite. However, when the Ni content is 10.0% or more, there is a high possibility of forming a regular phase such as Ni3Al, which may hinder the ductility at room temperature and cause shrinkage of the material to increase the density, Is set at 10.0%.

C: 0.5 to 1.0%

C is required not only for securing the strength of steel in the carbon steel component system but also for improving the strength by dispersing the Fe 3 AlC phase in the sintered body of the present invention. However, when it is added in an excessive amount, it may react with Fe and Al to excessively form Fe 3 AlC carbide precipitates, which may adversely affect impact properties by decreasing the consistency between precipitates and other metal phases. Therefore, the upper limit of the C content can be set at 1.0%.

According to one embodiment of the present invention, the sintered body of the present invention may further contain 0.3 to 1.0% of P, if necessary.

P: 0.3 to 0.7%

P is added to improve the impact properties of the material. When P is added in an amount of 0.3% or more, sintering at low temperature is improved, and the effect of increasing the strength and ductility can be obtained, and the pore can be rounded to improve the impact characteristics. However, excessive addition of P leads to excessive formation of precipitates such as Fe 3 P, resulting in deterioration of ductility and impact properties. Therefore, P can be added in the range of 0.3 to 0.7%.

The remainder other than the above-mentioned composition may be inevitable impurities which are incorporated into the sintered body in Fe and other manufacturing processes. As the impurities contained in the sintered body, there may be mentioned elements such as N, though not limited thereto. That is, N is an impurity inevitably contained in the manufacturing process, and is preferably contained as low as possible. Particularly, when the N content is more than 0.01%, the number of precipitates in the sintered body may increase and the ductility may be deteriorated. In particular, Fe 3 AlC may be finely dispersed by forming a high- DO3 < / RTI > < RTI ID = 0.0 > and / or < / RTI > Therefore, it is preferable that the N content is in the range of 0.01% or less.

The sintered body of the present invention is also characterized in that some of the newly formed BCC (BCC different from the BCC of the base structure) is formed in the base structure of the austenite (FCC) and ferrite (BCC) constituting the base powder constituting the sintered body ) And the B2 / DO3 regulated phase are dispersed. Since the BCC phase and the phase phase are formed in a size of 20 nm or less and separate from the base powder, the dispersion strengthening effect can be imparted to the sintered body. Therefore, when the cross section of the sintered body is observed with a microscope, it is preferable that the BCC phase and the regular phase include at least 5% in terms of area within the entire observation field (excluding voids). However, if the ratio is too large, the brittleness of the material may increase, and therefore, it is advantageous that the area of the entire observation field is 15% or less.

According to one embodiment, a C powder is added to the sintered body of the present invention as needed to form a precipitate such as Fe 3 AlC. The precipitate can also impart a dispersion strengthening effect in the sintered body. However, if the amount is excessive, it may increase the brittleness of the sintered body, so that it may be limited to 5% or less on the area basis.

The method for producing the sintered body of the present invention is not particularly limited as long as the sintered body having the above-described conditions can be obtained. However, one advantageous method is as follows.

A method of manufacturing a sintered body according to an embodiment of the present invention includes preparing and mixing each powder to satisfy a total composition of a proper sintered body; Powdering the mixed powder to obtain a green compact; And sintering the green compact at a high temperature to obtain a sintered body. Hereinafter, each process will be described in detail.

Step of mixing powder

It is necessary to prepare and mix each powder by the required amount so as to satisfy the content range of the sintered body described above. When the composition of the powder is determined, the composition of each powder for satisfying the entire composition of the sintered body can be easily determined by simple calculation, so that it is not particularly limited in the present invention. The mixing time of the powders is not particularly limited as long as the powders are sufficiently mixed. However, when the total weight of the powders is about 100 to 500 kg, the mixing time can be sufficiently uniform even with a mixing time of about 30 to 120 minutes. However, when the mixing time is excessive, the powder may be aggregated by mixing, so that the mixing of the powder can be stopped at an appropriate time while observing the mixing.

The step of pulverizing the mixed powder

Followed by pulverizing the mixed powder using a pressurizing device such as a press to form a green compact. Since the compact powder is a work to pressurize the mixed powder at a high pressure in order to improve the toughness and impact properties of the sintered body by reducing the amount of voids and to make a desired shape, sufficient pressure must be applied to the powder. According to one embodiment, the dust pressure of the present invention may be at least 600 MPa. The upper limit of the dust pressure is not particularly limited, but the dust pressure may be determined within a range of 900 MPa or less in consideration of a normal powder pressure.

Sintering the green compact

The green compact is sintered in a sintering furnace. In one embodiment of the present invention, sintering can be performed for a time period of about 30 to 40 minutes at a temperature range of 1100 to 1500 캜 so as to obtain a sufficient sintering strength and prevent excessive alloying or diffusion between the powders. In the sintering process of the present invention, the sintered body can have a high lightweighting ratio and impact toughness.

Hereinafter, the present invention will be described more specifically by way of examples. It should be noted, however, that the following examples are intended to illustrate and specify the present invention and not to limit the scope of the present invention.

(Example)

Example 1

(Fe-Ni powders) having various Ni contents as shown in Table 1 were prepared for each of the examples, and the mixing ratios (based on weight) of the Al, C and P powders were adjusted as shown in Table 1, And the powders were mixed. The Fe-Ni powder had a D ₅₀ of 90 탆 (all powders had a particle size of 250 탆 or less), and the other powder had a D ₅₀ of 50 탆 (100% powder had a particle size of 1 to 100 탆 Lt; / RTI > Among them, the Fe-Ni base powder and the Al powder have a particle size Span {(D ₉₀ -D ₁₀ ) / D ₅₀ } of 2.31 μm. In this embodiment, various kinds of known powders having different Ni contents were prepared in order to control the overall composition of the sintered body. However, in some cases, one type of known powders were prepared and Ni powder was added to obtain Ni powder It can also be adjusted. The total weight of the mixed powders was 5 kg, and the powders were mixed for 30 to 40 minutes for mixing. The mixed powder was compacted at a pressure of 600 MPa using a powder press to obtain a green compact. The green compact was then sintered in a belt furnace to obtain a sintered compact. The total composition (by weight) of the obtained sintered body is also shown in Table 1. Although each of the sintered bodies contained a part of nitrogen, it was confirmed that all of them had an impurity level of 0.01% or less and had no particular influence on the physical properties of the sintered body.

division Ni content (wt%) in Fe-Ni powder The ratio of the corresponding powder in the whole powder
(weight%) Total composition of sintered body
(weight%) Fe-Ni Al C P Fe Ni Al C P Inventory 1 8.00 93.7 5 0.8 0.5 86.2 7.5 5 0.8 0.5 Inventory 2 8.22 91.2 7.5 0.8 0.5 83.7 7.5 7.5 0.8 0.5 Inventory 3 8.46 88.7 10 0.8 0.5 81.2 7.5 10 0.8 0.5 Honorable 4 8.70 86.2 12.5 0.8 0.5 78.7 7.5 12.5 0.8 0.5 Inventory 5 8.96 83.7 15 0.8 0.5 76.2 7.5 15 0.8 0.5 Comparative Example 1 8.42 89.05 10 0.45 0.5 81.55 7.5 10 0.45 0.5 Comparative Example 2 8.48 88.45 10 1.05 0.5 80.95 7.5 10 1.05 0.5 Comparative Example 3 5.07 88.7 10 0.8 0.5 84.2 4.5 10 0.8 0.5 Comparative Example 4 11.84 88.7 10 0.8 0.5 78.2 10.5 10 0.8 0.5 Comparative Example 5 8.43 88.95 10 0.8 0.25 81.45 7.5 10 0.8 0.25 Comparative Example 6 8.48 88.45 10 0.8 0.75 80.95 7.5 10 0.8 0.75 Comparative Example 7 7.96 94.2 4.5 0.8 0.5 86.7 7.5 4.5 0.8 0.5 Comparative Example 8 9.01 83.2 15.5 0.8 0.5 75.7 7.5 15.5 0.8 0.5 Comparative Example 9 7.60 98.7 0 0.8 0.5 91.2 7.5 0 0.8 0.5

The density of the obtained sintered body (measurement density means an apparent density) and strength (here, the strength of the green compact means TRS (Transverse Rupture Strength)). That is, a green compact having a length of 31.8 mm, a width of 12.7 mm and a thickness of 6.4 mm is prepared, and the strength is measured by three-point bending. The sintered body was measured based on the tensile strength, and the impact energy of the sintered body (the result of the test using the Charpy impact test piece of 5 mm sub-size) and the weight reduction ratio are shown in Table 2. The weight reduction ratio {(1-measurement density /7.874)*100(%%}} was measured using the sintered body. The theoretical density is the maximum density that can be obtained when the porosity is absent when the specimen is made with each component. The density of the specimen having the actual porosity is measured by Archimedes principle. Where 7.874 means the density of Fe (g / cm ³ ).

division Theoretical density
(g / cc) Measurement density
(g / cc) Relative density Green compact
Strength (MPa) Sintered body
Strength (MPa) Shock energy
(J) Lightweight
(%) Inventory 1 7.008 6.412 0.915 15 210 97 18.6 Inventory 2 6.721 6.184 0.92 16 224 92 21.5 Inventory 3 6.457 5.973 0.925 18 252 84 24.1 Honorable 4 6.213 5.778 0.93 20 280 77 26.6 Inventory 5 5.987 5.598 0.935 21 294 70 28.9 Comparative Example 1 6.504 6.016 0.925 9 126 108 23.6 Comparative Example 2 6.425 5.943 0.925 25 350 45 24.5 Comparative Example 3 6.439 5.859 0.91 18 252 52 25.6 Comparative Example 4 6.476 6.120 0.945 23 322 62 22.3 Comparative Example 5 6.502 6.014 0.925 17 238 58 23.6 Comparative Example 6 6.414 5.933 0.925 19 266 45 24.7 Comparative Example 7 7.068 6.446 0.912 13 182 82 18.1 Comparative Example 8 5.944 5.569 0.937 22 308 65 29.3 Comparative Example 9 7.661 6.972 0.91 12 168 102 11.5

As can be seen from the above Table 2, in the case of the invention example satisfying the entire composition of the sintered body proposed by the present invention, it was confirmed that the strength of the sintered body was not less than 200 MPa and the impact energy was not less than 70 J, .

Compared with the comparative example 1, it is found that the C content is less than the range specified in the present invention, and the strength of the sintered body is only 126 MPa. In Comparative Example 2, the C content exceeded the range specified in the present invention, indicating that the impact strength is high but the impact energy is only 45 J, which means that the toughness is poor.

Similar results can be confirmed in Comparative Example 3/4, Comparative Example 5/6, and Comparative Example 7/8. That is, in Comparative Example 3, the content of Ni is less than the range specified in the present application, but the impact energy is 52 J, which means that the toughness is insufficient. In Comparative Example 4 where the Ni content was as high as 10.5, the impact energy was also low as 45 J, which was also considered to be an adverse effect on the toughness due to a large amount of Ni 3 Al generated in the regular state of Ni and Al.

Comparative Example 5 is a case where the content of P is insufficient, but the strength is good but the impact energy is 58J, which is poor. In Comparative Example 6, the P content was excessive, which also showed low impact energy.

Comparative Example 7 shows a case where the Al content is low, but not only the strength is insufficient, but the lighter weight ratio is only 18.1%, indicating that it does not exhibit a sufficient weight reduction ratio. Comparative Example 8, on the contrary, showed a case where the Al content was excessive, and the impact energy was insufficient. Comparative Example 9 is a case where a sintered body was produced using only the base powder, the C powder and the P powder without adding any Al powder. However, it is confirmed that not only the strength is sufficient but also the weight reduction ratio is insufficient.

Example 2

Apart from the above experiment, the same Fe-Ni powder as in Inventive Example 1 of Example 1 was used, and while the content of the C powder and the P powder was maintained, the content of the Al powder was changed The weight ratio of the sintered body was confirmed after the sintered body was manufactured by the same mixing, compaction and sintering conditions as in Example 1, and the weight reduction ratio of the casting material having the same overall composition as that of the sintered body was compared 2.

As can be seen in the figure, it was confirmed that the lightening rate increased with the increase of the Al content, but the sintered body had a weight reduction ratio of about 5% higher than that of the cast material. This shows that the sintered body has high strength and toughness and can meet the high light weight required for lightweight materials.

Example 3

As a result of observing the cross section of the sintered body manufactured in Example 2 using SEM, it was confirmed that the BCC phase and the regular phase (B2 / DO3) were occupied at an areal ratio of 7.5% And it was confirmed that it was finely dispersed in the base. The Fe 3 AlC phase also existed in the sintered body, and the occupation ratio thereof was 3% based on the area.

FIG. 3 is a photograph showing that the sintered body produced in Inventive Example 2 has a regular B2 / DO3 and austenite structure. It can be confirmed from the photograph on the upper left side of the figure that the B2 phase exists (corresponding to the dark part in the drawing). The B2 phase can exhibit a dispersion strengthening effect in the sintered body. In addition, it was confirmed that the DO3 phase can be generated, though not specifically shown in the photograph, and it was confirmed that this is also effective for dispersion enhancement.

As described above, the sintered body produced by the present invention is obtained by sintering the known powder and the aluminum powder. In addition to being able to solve the problem of toughness deterioration due to excessive formation in the rule unlike the casting material, Which is excellent in the performance as a lightweight material.

Claims

A sintered body obtained by sintering an Fe-Ni powder, an Al powder and a C powder each containing 5.5 to 11.0 wt% of Ni,
5.0 to 15% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, balance Fe and other unavoidable impurities in the weight ratio of the whole composition.

delete

The light-weight sintered body according to claim 1, wherein the Fe-Ni powder has a proportion of austenite structure before sintering of 30 to 80% by area.

The light-weight sintered body according to claim 1, further comprising P powder so as to have a total composition including 0.3 to 0.7% of P by weight.

Ni powder, Ni powder, Ni powder, Ni powder, Ni powder and Ni powder containing 5.5 to 11.0 wt%
Wherein the whole composition comprises 5.0 to 15% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, 0.3 to 0.7% of P, and the balance of Fe and other unavoidable impurities in the weight ratio.

Ni powder, Ni powder, Al powder and C powder containing 5.5 to 11.0 wt% of Ni,
5.0 to 15% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, balance Fe and other unavoidable impurities in the weight ratio of the whole composition.

Of claim 1 and claim 3 to claim 6 according to any one of claims, wherein the Fe-Ni powder D ₅₀ is 70 ~ 100㎛, and more than 99% of the number of light-weight powder sintered body having a grain size of less than 250㎛.

The light-weight sintered body according to claim 7, wherein the Fe-Ni powder has a particle size span {(D ₉₀ -D ₁₀ ) / D ₅₀ } of 3.0 or less.

7. The method of any one of claims 1 to 6, wherein the Al powder, the C powder, and the P powder have a D ₅₀ of 40 to 60 탆, and 99% or more of the number of the powder has a particle size of 100 탆 or less Light weight sintered body.

10. The method of claim 9, wherein the Al powder is the span _{(Span) {(D 90 -D} 10) / D 50} is 3.0 or less weight of the sintered body size.

7. The lightweight sintered body according to any one of claims 1 to 6, wherein the BCC phase and the ordered phase of Fe-Al are contained in an area ratio of 5 to 15%.

12. The lightweight sintered body according to claim 11, wherein the regular size of Fe-Al on the BCC is 20 nm or less.

5.0 to 15.0% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, Fe of the remainder and Fe and other inevitable impurities of Fe-Ni powder, Al powder and C powder containing Ni in a range of 5.5 to 11.0% Preparing a mixed mixture having a total composition including impurities;
Milling the mixture to obtain a green compact; And
And heating the mixture at a high temperature to obtain a sintered body.

14. The method of manufacturing a light weight sintered body according to claim 13, wherein the mixture further comprises P powder so that the total composition further comprises 0.3 to 0.7% of P by weight.

5.0 to 15% of Al, 5.0 to 10.0% of Ni, and 0.5 to 1.0% of C, in terms of weight ratio, of Fe-Ni powder, Ni powder, Al powder, C powder and P powder containing Ni in an amount of 5.5 to 11.0% , P: 0.3 to 0.7%, the balance Fe and other unavoidable impurities;
Milling the mixture to obtain a green compact; And
And heating the mixture at a high temperature to obtain a sintered body.

5.0 to 15% of Al, 5.0 to 10.0% of Ni, 0.5 to 1.0% of C, 0.5 to 1.0% of C, and the balance of Fe, Ni powder, Ni powder, Al powder and C powder containing 5.5 to 11.0% And other unavoidable impurities to form a mixture having a total composition;
Milling the mixture to obtain a green compact; And
And heating the mixture at a high temperature to obtain a sintered body.

17. The method of manufacturing a light weight sintered body according to any one of claims 13 to 16, wherein the compacting step presses the mixture at a pressure of 600 MPa or more.

The method of manufacturing a lightweight sintered body according to any one of claims 13 to 16, wherein the heating is performed at a temperature of 1100 to 1500 占 폚 for 30 to 40 minutes.