JPS58130259A - Sintered fe alloy with superior wear and corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain a sintered Fe alloy with superior wear and corrosion resistances by adding specified percentages of Cr, C, Ni, Co, Nb, Ta and Zr to Fe and by uniformly dispersing a metallic carbide and an intermetallic compound in the matrix. CONSTITUTION:An alloy consisting of, by weight, 5-25% Cr, 0.5-1.2% C, 1- 25% Ni and/or Co, 1-15% one or more among Nb, Ta, Zr and Ti and the balance Fe with inevitable impurities or further contg. 0.3-5.0% Mo and/or W, and/or <=5.0% in total of one or more among 0.1-2.0% P, 0.01-1.0% B and 0.1-3.0% Si is prepared. This alloy is manufactured by a conventional powder metallurgical method under conventional conditions, and it has a structure contg. a metallic carbide and an intermetallic compound dispersed uniformly in the matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has excellent wear resistance and corrosion resistance, as well as excellent compatibility, and is particularly applicable to submersible pumps, alcohol, alcohol-containing gasoline, and denatured fuel, which require these characteristics. Fe is suitable for use in transportation parts such as, seal rings and rotors in these fuel injection pumps, and valve device structural parts of exhaust gas recirculation devices of gasoline engines and diesel engines.
This invention relates to base sintered alloys.

Conventionally, in the manufacture of structural members for various pumps of the above type, valve device structural members for exhaust gas recirculation equipment, etc., materials that have wear resistance, corrosion resistance, and conformability are generally used due to the environmental conditions in which they are used. Materials are used for each axis, but these materials do not necessarily have satisfactory properties, and in particular, they do not have properties that are sufficient to cope with the harsher operating conditions that accompany the recent improvements in the performance of various types of equipment. The current situation is that there is no such thing.

Therefore, from the above-mentioned viewpoint, the present inventors have conducted research to find materials suitable for manufacturing structural members of various pumps and valve device structural members of exhaust gas recirculation devices, etc. As a result, they have found that, in weight percent, Cr: 5-25%, C205-1.2%, Ni
and one or two of co: 1 to 25%, N
Contains 1-15% of one or more of b, Ta, Zr, and T1, and further 3-5.0% of one or two of MO and W as necessary.
Contains P: 01-2.0%, B as necessary.
:0.01-1.0%, and Si, :0.1-3.0
% or more (however, the content is 5.0%)
Fe-based sintered alloys have a composition in which the remainder consists of Fe and unavoidable impurities, and have a structure in which metal carbides and intermetallic compounds are uniformly dispersed in the matrix, and have excellent wear resistance. It has excellent corrosion resistance and conformability,
Therefore, we have found that the Fe-based sintered alloy exhibits excellent performance when used as structural members of the various pumps mentioned above, valve device structural members of exhaust gas recirculation devices, and the like.

This invention was made based on the above findings, and the reason why the component composition range was limited to the above-mentioned 9 will be explained below.

(Al Cr The Cr component is contained for the purpose of imparting corrosion resistance and oxidation resistance to the alloy, but if the content is less than 5%, the desired corrosion resistance and oxidation resistance cannot be secured;
Even if the content exceeds 5%, no further improvement effect will appear due to the above-mentioned properties, but rather a tendency to decrease in toughness will appear, so the content was set at 5 to 25%.

(b) c The C component includes Nb, Ta, Ti, and Zr.
, further combines with W and Mo to form metal carbides that are uniformly dispersed in the base material, thereby improving the wear resistance of the alloy, and the residual part dissolves in the base material to strengthen it. However, if the metal carbide content is less than 0.5%, the amount of metal carbide is too small to ensure the desired wear resistance, while if the content exceeds 1.2%, metal carbide will be absorbed into the substrate. Since the amount of solid solute C and the amount of Cr carbide are too large and the corrosion resistance deteriorates, the content should be reduced from 0.5 to 1.
．． It was set at 2%.

(c) Ni and C.

These components include Nb, Ta, Zr, Ti,
Furthermore, Mo.

It reacts with W to form a hard intermetallic compound that is uniformly dispersed in the matrix, thereby improving the wear resistance and conformability of the alloy, and forming a eutectic to improve sinterability. When dissolved in solid solution in the base material, it has the effect of strengthening the base material and improving its corrosion resistance, but if its content is less than 1%, the desired effect cannot be obtained; on the other hand, even if it is contained in excess of 25%, Since no further improvement effect was observed, the content was determined to be 1 to 25%, taking economic efficiency into account.

(d) Nb, Ta, Zr, and T1 These components, in addition to reacting with C to form extremely hard metal carbides as described above, also contain N1°Co, Mo,
It also reacts with W to form a hard intermetallic compound, which improves the wear resistance and conformability of the alloy.
It forms a eutectic with Co, Mo, and W, and as a result, a liquid phase is generated at a relatively low temperature, which has the effect of improving the density of the alloy. If it is less than 1%, the desired effect cannot be obtained;
If the content exceeds 5%, the toughness decreases, so the content was set at 1 to 15%.

In addition, these components have stronger reactivity with C than other alloy components and have the property of preferentially forming carbides, so their content should be determined by satisfying the formula: %Formula %) It is desirable to do so.

(e) Mo and W These components not only solidly dissolve in the base material and strengthen it, but also react with Ni, Co, Nb, Ta, Zr, and 1゛1 to form hard intermetallic compounds. However, since it has the effect of hardening the alloy, it is included as necessary when even higher strength and hardness are required, but if the content is less than 0.3%, the desired improvement in the above effect is not achieved. However, if the content exceeds 5%, the toughness decreases, so the content was reduced to 0.3%.
It was set at ~5.0%.

(f) P, B, and Si These components not only improve sinterability and densify the alloy, thereby further improving corrosion resistance, but also dissolve in solid solution in the base material to further strengthen it. It is included as necessary when these properties are required because of its effectiveness.
The content is P: less than 0.1%, B: 0.0
If the amount of S is less than 1% and the amount of S is less than 201%, the desired effect of improving the above action cannot be obtained. If a component is contained, if the content exceeds 5%, the toughness and corrosion resistance tend to deteriorate.
0%, B: 0.01-1.0%, Si:
It was set at 0.1 to 3% (however, P10B+si: 5.00 or less).

Next, the Fe-based sintered alloy of the present invention will be specifically explained using Examples.

Examples of raw material powders include Ni-Nb alloy (containing 54% Nb) powder and Fe-Ni powder with a particle size of -20 Omesh.
-Nb alloy (Ni: 35%, Nb: 52% content) powder,
Fe-Co-Nb alloy (Co: 45%, Nb: 4
7% containing) powder, Fe-Ni-Ta alloy (Ni:3
4%, Ta: 53%) powder, Fe-Ni-Ti alloy (Ni: 30%, Ti: 65%) powder,
Fe-Ni-Zr alloy (Ni-10%.

Zr: Contains 82m) powder, both of which contain 150m
esh Fe-Cr-Nb alloy (Nb: 8.1%
, C'r: 12.8%) powder, Fe-0
r-Nb alloy (Nb: 8.0%, Cr; 5,5
% content) powder, Fe-Cr alloy (Cr: 14% content) powder, Fe-Cr alloy (Cr: 31.3% content) powder
powder.

Fe-Cr-Nb alloy (Cr: 11.5%, Nb near,
3% containing) powder, same (-100 mesh atomized iron powder.

-l OOmesh flaky graphite, all with average particle size: 3 μm N1 powder, Co powder, Mo powder, and V
7 powders, all of which have particle size: -20Omesh F
, ::-P alloy (P: 26.6% content) powder, Fe-B
Alloy (containing 20% B) powder, Fe-Si alloy (Si:
42% containing) powder and N1-P alloy (P: 12% containing) powder were prepared, and these raw material powders were blended into the composition shown in Table 1, and mixed for 30 minutes in a MyNut mixer. , 5 to 6 tons/cI/L of pressure to form a green compact, and then the green compact was heated in a vacuum furnace at 1240 ton/cI/L.
It is heated to a predetermined temperature within the temperature range of ~1300°C and sintered, and in the cooling process after sintering, it is rapidly cooled from a predetermined temperature within the temperature range of 1000 to 1050°C, and then to a temperature of 500 to 540°C. Sintered alloys 1 to 37 of the present invention and comparative sintered alloys 1 to 5 having substantially the same final component composition as the blended composition were manufactured by aging under the condition of holding for 2 hours. The structures of the various sintered alloys obtained as a result were observed using a microscope.

All of the present invention sintered alloy 1-737 and comparative sintered alloy 1
-4 had a structure in which metal carbide and intermetallic compound were uniformly dispersed in the base material. On the other hand, comparative sintered alloy 5 uses -150 mesh Fe-
Cr alloy (Cr: 12.6% content) powder, -2
By using TiC powder of 00 mesh, flaky graphite of -100 mesh, and N1 powder of average particle size of 3 μm, although the composition is within the composition range of the Fe-based sintered alloy of the present invention, It is a structurally different alloy in that there is no formation of intermetallic compounds.

Comparative sintered alloys 1 to 4 have compositions in which the content of any one of the constituent components (indicated by * in Table 1) is outside the scope of the present invention.

These sintered alloys were then subjected to wear resistance tests and corrosion resistance tests.

The abrasion resistance test used a test piece with dimensions of 10 IIXIO and 30 mm, and a surface pressure of a rotating ring made of 5US420 (hardness: HRC50) with a diameter of 30 mm and a diameter of 5 mm and a thickness of 5 mm was applied to this test piece. : 6 at 9/cd, and the rotating ring was heated at 2000 r in degraded gasoline containing 3% H7O.
The test piece was rotated at a rotational speed of 20 G, and the wear depth of the test piece was determined to be 1l111 after 20G time had elapsed.

In addition, the corrosion resistance test was conducted by observing the state of rust after being left for 20 hours in an atmosphere with a temperature of 35°C and a humidity of 95°C. The evaluation was made with an O mark, and a considerable amount of rust was marked with an X mark.

These results are shown in Table 1 together with the density.

From the results shown in Table 1, sintered alloys 1 to 37 of the present invention all have excellent wear resistance and corrosion resistance, whereas comparative sintered alloy 1 whose component composition is outside the scope of the present invention. - 4 and Comparative Sintered Alloy 5, which has a composition within the scope of the present invention but is structurally different in that no intermetallic compound is formed, has at least one of wear resistance and corrosion resistance. It has become inferior.

As mentioned above, the Fe-based sintered alloy of the present invention has excellent wear resistance and corrosion resistance, and is also excellent in toughness, so it is particularly suitable for seal rings of various types of ponnos that require these properties. When used as valve equipment components or underwater sliding components in exhaust gas recirculation systems for various internal combustion engines, it exhibits excellent performance over an extremely long period of time even under harsh conditions. That's what I do.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo

Claims (4)

[Claims] (1) Cr: 5-25%, C: 0.5-1
．． 2%, one or two of Ni and CO: 1-
25%, Nb. Contains one or more of Ta, Zr, and T1 = 1 to 15%, has a composition (or more by weight) with the remainder consisting of Fe and unavoidable impurities, and has metal carbide and metal carbide in the matrix. An Fe-based sintered alloy with excellent wear resistance and corrosion resistance, characterized by having a structure in which intermetallic compounds are uniformly dispersed. (2) Cr: 5-25%, C: 0.5-1
．． 2%, one or two of Ni and Co: 1
~25% Nb. Contains 1-15% of one or more of Ta, Zr, and T1, and further contains one of MO and W.
Species or 2 species: Contains 0.3 to 5.0%, with the remainder being F.
having a composition (more than % by weight) consisting of e and unavoidable impurities,
An Fe-based sintered alloy having excellent wear resistance and corrosion resistance, and having a structure in which metal carbides and intermetallic compounds are uniformly dispersed in the matrix. (3) Cr: 5-25%, C: 0.5-1
．． 2%, one or two of Nj and Co = 1 to
25%, Nb. Contains 1 to 15% of one or more of Ta, Zr, and T1, and further P: 0.1 to 20%. B: O, Ol ~1.0%, and Si: 0.1~3
．． One or more of 0% (however, 5% in content)
．． 0% or less), has a composition (weight% or more) in which the remainder is Fe and unavoidable impurities, and has a structure in which metal carbides and intermetallic compounds are uniformly dispersed in the matrix. Fe-based sintered alloy with excellent wear resistance and corrosion resistance. (4) Cr: 5-25%, C: 0.5-1
．． 2%, one or two of Nl and co: 1
~25% Nb. Contains one or more of Ta, Zr, and Ti = 1 to 15 Ti, and further contains one of MO and W.
Species or 2 types: 03-5.0%, P: 01-20%,
B: Contains one or more of O○1-1.0% and Si: 0.1-30% (however, the content is 5.0% or less), and the remainder is Fe and unavoidable impurities. A composition consisting of (
% by weight) and has a structure in which metal carbides and intermetallic compounds are uniformly dispersed in the matrix, and has excellent wear resistance and corrosion resistance.