JPS58224154A - Sintered fe alloy for valve seat of internal combustion engine - Google Patents

Abstract

PURPOSE:To obtain a sintered Fe alloy for the valve seats of an internal combustion engine with superior resistance to wear, heat, corrosion and oxidation by adding specified amounts of C, Mo, Ni and Cr to a steel and by providing a specified density to the resulting alloy as sintered. CONSTITUTION:The composition of this sintered Fe alloy for the valve seats of an internal combustion engine is composed of, by weight, 0.5-2% C, 3.5-13% Mo, 6-12% Ni, 1-6% Cr and the balance Fe with inevitable impurities, and >=7g/cm<3> density is provided to the alloy as sintered. 0.1-5% Co, 0.1-5% Cu or 0.05-0.4% S may be added furthermore. Since the alloy has said high density as sintered, it is not required to increase the density by coining, hot or cold forging or other method, so the alloy is obtd. at a reduced cost.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides high density and high strength of t, ol//cr1 or more, and excellent wear resistance, heat resistance, and corrosion resistance.

F'e-based combustion has excellent oxidation resistance and exhibits excellent performance when used as a valve seat for internal combustion engines, which are becoming more diversified, more compact, and have higher performance. It concerns bond money.

In recent years, sintered alloys have come into widespread use in the manufacture of valve seats for internal combustion engines. This is because sintered alloys have high productivity (economic efficiency), and the unique structure and pores of sintered alloys effectively affect the performance of internal combustion engine valve seats.

However, with the recent diversification, miniaturization, and high performance of internal combustion engines, the operating conditions for valve seats are becoming increasingly severe. On the contrary, the porosity that it has causes it to become an obstacle and does not exhibit the desired durability.

Therefore, the pores that cause durability deterioration in sintered alloy valve seats are increased by coining, hot or cold forging, etc. to increase the density, and even more carbon atoms are added to the pores.
Attempts have been made to improve durability by impregnating it with U, PB, etc., but all of these methods increase costs and are problematic in terms of economy.

From the above-mentioned viewpoint, the present inventors have achieved high density in the as-sintered state without requiring density-improving means such as coining, forging, or even metal impregnation, which increase costs. In order to obtain a valve seat for an internal combustion engine that exhibits excellent durability (performance) even under harsh operating conditions,
As a result of research from the material aspect, the weight ratio was C: 0.5.
~2.0%.

Mo: 3.5-13.0%, Ni: 6-12%, Cr
Co: 1 to 6%, and optionally Co: 0.1
~5%, Cu: 0.1~5%, and S: 0.
Fe-based sintered alloys containing one or two of 05 to 0.4% and the remainder consisting of Fe and unavoidable impurities have high t, ogla, and L in the as-sintered state. It has high density and high strength, as well as excellent wear resistance and heat resistance.

When Fe-based sintered alloys with corrosion and oxidation resistance are used in the manufacture of internal combustion engine valve seats, the resulting valve seats have excellent durability (performance) even under severe service conditions.
We obtained the knowledge that this shows that

This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below.

(a) C The C component has the effect of forming a solid solution in the base material and strengthening the wear resistance, as well as forming carbides and improving wear resistance, but if the content is less than 0.5%, the above effect will not occur. On the other hand, if the content exceeds 2.0%, the formability of the green compact deteriorates, the sheathing and rigidity of the sintered alloy deteriorate, and there is a tendency for embrittlement. appears and the aggressiveness towards the valve, which is the mating material, increases, so its content was set at 0.5 to 2.0%.

(b) M.

The Mo component has the effect of combining with the C component to form carbide and improving wear resistance, and also has the effect of solid solution in the base material to improve heat resistance and corrosion resistance. If the content is less than 3.5%, the desired effect cannot be obtained in the above action, and on the other hand, if the content exceeds 13.0%, the effect of further improving the action will not appear, but rather there will be a tendency for the density and strength to decrease. Therefore, the content was determined to be 3.5 to 13.0%, taking economic efficiency into consideration.

(c) Ni The Ni component significantly improves the density, and the sintered alloy
It is an essential component in order to have a high density of 1cr1 or more, and it also has the effect of improving strength and heat resistance, but if its content is less than 6%,
7.0 F/, lcr! Not only is it not possible to secure a higher density than above, but the strength and heat resistance are also insufficient, and on the other hand, even if the content exceeds 12%, there is no significant improvement effect, and the viscosity increases. The content was set at 6 to 12% because the stiffness deteriorates when the content is lowered.

(d) Cr Similar to Mo, Crt539 combines with the C component to form carbide, thereby improving wear resistance, and also dissolves in the base material to improve corrosion resistance and oxidation resistance. However, if the content is less than 1% or 4%, the desired effect cannot be obtained, while if the content exceeds 6%, the density will be 7%. The content was determined to be 1 to 6% because if the content was less than ol/cr/l, the strength would decrease, and the hardness would increase, making the opponent more aggressive.

(eJ C.

The co-acid component dissolves in the base material and improves heat resistance (red-hot hardness).
Since it has the effect of increasing the Even if the content exceeds 0.0%, no further improvement effect will be obtained, and in consideration of economic efficiency, the content was set at 0.01 to 6.0%.

(f) Cu A part of the Cu component dissolves into the base material to improve induction resistance, promotes sinterability, increases density, and further improves thermal conductivity and welding resistance. It has the effect of causing
This effect becomes even more pronounced in coexistence with N1, so it is included as necessary when these properties are required, but if the content is less than 0.1%, the desired effect of improving the above effect may not be achieved. On the other hand, if the content exceeds 5%, the wear resistance will decrease and the crystal grains will become coarser, increasing the wear of the valve that is the mating material. It was set at 0.1 to 5 inches.

(g) SS The S component has the effect of improving the rigidity of the alloy and improving the compatibility with the valve, which is the mating material, and these effects become particularly noticeable when coexisting with Co. Therefore, it is included as necessary when these properties are required, but if the content is less than 0.05%, the desired effect of improving the above function cannot be obtained, while if the content is less than 0.40%
Since the strength will decrease if the content exceeds 0.05% to 0.40%. In addition, it is preferable to contain 01 to 0.2.

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

Examples of raw material powders include atomized iron powder with a particle size of -100 mesh and Fe-Cr alloy (Cr:
12%) powder, same 100 mesh carbon powder, same 4
00mesh carbonyl N1 powder, same 200mesh
h Fe-Mo alloy (Mo: 58% content) powder, same 2
Co powder of 00 mesb, Cu powder of the same 250 mesh, and F'e-8 alloy (8
21% (containing 21%) powder was prepared, and these raw material powders were blended into the composition shown in Table 1, mixed for 15 minutes in a MyNut mixer, and then molded into a valve seat shape under a pressure of 6 t, on/cIl. By molding the powder into a green compact and then sintering each green compact in a hydrogen atmosphere at a temperature within the temperature range of 1140 to 1180°C for 1 hour, the mixture composition can be substantially changed. Valve seats 1 to 34 made of sintered alloy of the present invention having the same final component composition. Comparative sintered alloy valve seat 1~
11. and a conventional sintered metal valve seat, which has been widely used as a valve seat for internal combustion engines, were manufactured.

In addition, all of the comparative sintered metal valve seats 1 to 11 have a composition in which the content of one of the constituent components (those marked with * in Table 1) is outside the scope of the present invention. It is something.

Next, the resulting valve seats 1 to 3 made of the sintered alloy of the present invention
4. Comparative sintered alloy valve seats 1 to 11. The density and Vickers hardness of the conventional sintered alloy valve seat were measured, and a valve seat wear tester simulated in a practical engine was used to measure the valve seat.Valve material: austenitic steel for valves, valve filling degree: 850℃
, Valve shaft amount: 26.8 mm, Seated load: aokg, Rotation speed: 300 Or, p, m, , Atmosphere: LPG combustion gas, Test time: 2 hours, Durability and wear tests were carried out.
Total subsidence wear and valve seat wear were measured. These measurement results are also shown in Table 1.

From the results shown in Table 1, valve seats made of sintered alloy of the present invention 1 to
34 is 7,011/art in the as-sintered state.
In addition to having a high density of 7.0)7/ci or less, it also has extremely high hardness compared to conventional sintered alloy valve seats, which have a density of 7.0)7/ci or less and relatively low hardness. It has outstanding abrasion resistance and is also highly resistant to attack by opponents (
It is clear that the total subsidence wear amount - valve seat wear amount - wear amount of the mating valve material is also low.

Furthermore, as seen in the comparative sintered alloy valve seat, if the content of any one of the constituent components falls outside the scope of the present invention, at least one of the density, wear resistance, and aggressiveness against the other party will be affected. It can be seen that the character of the person becomes inferior.

As mentioned above, the Fe-based sintered alloy of the present invention has a yield of 7.0#/c in the as-sintered state! It has a high density and high strength, as well as excellent wear resistance, heat resistance, corrosion resistance, and oxidation resistance, so it is used especially for manufacturing valve seats used under harsh conditions. Excellent durability (performance) when
This is achieved over an extremely long period of time.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo

Claims (1)

[Claims] (1) c: 0.5-2.0%, Mo: 3.5-2.0%
13.0%. Internal combustion characterized by having a composition (by weight %) containing Ni: 6 to 12%, Cr21 to 6%, and the remainder consisting of Fe and unavoidable impurities, and a density near, oIi / 7 or more. Fe-based sintered alloy for engine valve seats. (2) C: 0.5-2.0%, Mo: 3.5
~13.0'%. Contains Ni: 6 to 12%, Cr: 1 to 6%, further contains Co: 0.1 to 5%, and the remainder is Fe and unavoidable impurities (wt%), density near,
0,! An Fe-based sintered alloy for a valve seat of an internal combustion engine, characterized in that it has i'/a1 or more. (3) C: O, 5-2.0%, Mo: 3.
5-13.0%. Contains N1: 6-12%, Cr: 1-6%, and has a smooth C
u: Contains 0.1 to 5%, the rest is Fe and unavoidable impurities.
Composition consisting of (more than weight Rano and density Nia,
? 1. An Fe-based sintered alloy for a valve seat of an internal combustion engine, characterized in that it has a sintered alloy of '/crA or more. (41C: 0.5-2.0 tou, Mo: 3.5-13.0
blood. Contains Ni: 6 to 129%, Cr: 1 to 6%,
Further, the composition contains S: 0.05 to 0.4 yen, and the remainder is Fe and inevitable impurities (weight ratio), and density: 7. An Fe-based sintered alloy for a valve seat of an internal combustion engine, characterized by having Oylcr&F. (51C: 0.5~2.0%, Mo: 3.5~
13.0%. Contains Ni: 6-12'ib, Cr: 1-6%, further Co: 0.1-5% and Cu: 0.1-6%.
Composition (wt%) and density: 7.01! /cnt
F for a valve seat of an internal combustion engine, characterized by having y, l.
e-based sintered alloy. (+5) C: 0.5-2.096. Mo: 3
．． 5-13. Oqb. Contains 6 to 12 H of N, 1 to 6 H of Cr, and further Co.
: 0.1 to 5% and S: 0.05 to 0.4%, with the remainder consisting of F's and unavoidable impurities (wt%), and density: 7.0 g/d or more. An Fe-based sintered alloy for a valve seat of an internal combustion engine, characterized by having -L. (7) C: 0.5-2.0%, Mo: 3.
5-13.0%. Contains Nl: 6-12%, Cr: 1-6%,
Furthermore, Cu: 01-5% and 8: 0.05-0.
An Fe-based sintered alloy for a valve seat of an internal combustion engine, characterized by having a composition (by weight) of Fe and unavoidable impurities, and a density of near oEtlcr of 1 or more. (8) C: 0.5-2.0%, Mo: 3.5
~13.0%. Contains N1: 6-12%, Cr: 1-6%, further Co: 0.1-5%, Cu: 0.1-5%,
and S: 0.05 to 0.4%, with the remainder consisting of Fe and unavoidable impurities (weight ratio), and a valve seat for an internal combustion engine characterized by having a density near, oll/dt or more. Fe-based sintered alloy for use.