Hitachi Powdered Metals Co., Ltd.

Nissan Motor Company Limited

Other

Honda Giken Kogyo Kabushiki Kaisha

Mitsubishi Steel Mfg. Co., Ltd.

Yoshimasa Aoki

Koichiro Hayashi

Kei Ishii

Koichi Aonuma

Hideaki Kawata

Akira Fujiki

Kunio Maki

Atsushi Ehira

Keitaro Suzuki

Katsuyuki Nakamura

Makoto Tsuji

Hideo Urata

Yutaka Ikenoue

Masaki Toriumi

Koji Koishikawa

Yuji Soda

Toru Tsuboi

Yukio Tokuyama

Sadayuki Abo

Kouichi Aonuma

Seigo Sato

The invention relates to an iron-based high-temperature wear-resistant sintered alloy. This alloy contains 3.74-13.36 wt % W, 0.39-5.58 wt % V, 0.2-5.78 wt % Cr, 0.1-0.6 wt % Si, 0.39-1.99 wt % Mn, 0.21-1.18 wt % S, and up to 2.16 wt % C. This alloy includes 20-80 wt % of a first phase and 80-20 wt % of a second phase, each distributed therein, in the form of spots. The first phase contains 3-7 wt % W, up to 1 wt % Cr, 0.1-0.6 wt % Si, 0.2-1 wt % Mn, 0.1-0.6 wt % S, and up to 2.2 wt % C. The first phase may contain 0.5-1.5 wt % V, and in this case the vanadium content of the alloy becomes 0.79-5.88 wt %. The second phase contains 7-15 wt % W, 2-7 wt % V, 1-7 wt % Cr, 0.1-0.6 wt % Si, 0.2-1 wt % Mn, 0.1-0.6 wt % S, and up to 2.2 wt % of C. Each phase contains 0.3-1.6 wt % MnS and a carbide of at least tungsten, which are dispersed therein. The second phase further contains 10-20 areal % tungsten carbide (particle diameter: &gE;1 &mgr;m) dispersed therein. The alloy further contains 0.3-16 wt % MnS grains dispersed in grain boundaries and/or pores. The alloy is greatly improved in wear resistance, while suppressing damage to mating part in contact with the alloy.

High-temperature wear-resistant sintered alloy

The present invention provides a sintered material having high mechanical strength and superior wear resistance, and to a process of manufacture therefor. A sintered alloy having superior wear resistance has an overall composition consisting of, in percent by weight, Ni in an amount of 6.0 to 25.0%, Cr in an amount of 0.6 to 8.75%, C in an amount of 0.54 to 2.24%, and balance consisting of Fe, the sintered alloy exhibiting a metallographic structure in which the following hard phase is dispersed in a mixed structure of martensite and austenite, the hard phase comprising a core consisting of Cr carbide and a ferrite phase diffused Cr, or a mixed phase of ferrite and austenite diffused Cr, surrounding the core, and an area ratio of austenite in the mixed structure in the metallographic structure ranging from 5 to 30%.

Sintered alloy having superior wear resistance

A sintered alloy having superb wear resistance comprising: composite phases dispersed in a matrix of the sintered alloy; the composite phase consisting of; a particle group in which Cr carbide particles and Cr sulfide particles exist in a mixed condition; and a ferrite phase or a mixture phase of ferrite and austenite surrounding the particle group as a core.

Sintered alloy having superb wear resistance and process for producing the same

The invention relates to a sintered alloy. This sintered alloy includes 3-13.4 wt % of W, 0.4-5.6 wt % or 0.8-5.9 wt % of V, 0.2-5.6 wt % of Cr, 0.1-0.6 wt % or 0.6-5.0 wt % of Si, 0.1-0.6 wt % or 0.2-1.0 wt % of Mn, 0.6-2.2 wt % of C, and a balance of Fe. The sintered alloy includes first and second phase which are distributed therein, in a form of spots, respectively. The second phase is in an amount of from 20 to 80 wt %, based on the total weight of the first and second phases. The first phase contains 3-7 wt % of W, 0.5-1.5 wt % of optional V, up to 1 wt % of Cr, 0.1-0.6 wt % or 0.6-5.0 wt % of Si, 0.1-0.6 wt % or 0.2-1.0 wt % of Mn, up to 2.2 wt % of C, and a balance of Fe. The second phase contains 3-15 wt % of W, 2-7 wt % of V, 1-7 wt % of Cr, 0.1-0.6 wt % or 0.6-5.0 wt % of Si, 0.1-0.6 wt % or 0.2-1.0 wt % of Mn, up to 2.2 wt % of C, and a balance of Fe. When the manganese contents of the first and second phases and the total of the sintered alloy are respectively in a range of from 0.2 to 1.0 wt %, sulfur is respectively contained therein in an amount of from 0.1 to 0.6 wt %. The sintered alloy has wear-resistant at high temperature and good compatibility without damaging mating part that is in contact with the sintered alloy.

The present invention provides a valve seat having a suitable degree of wear resistance, which can be produced without recourse to expensive elements represented by cobalt and at a cost lower than ever before. This valve seat is formed of a wear-resistant sintered alloy having a general composition consisting essentially of, in weight ratio, 0.736 to 5.79% of nickel, 0.12 to 6.25% of chromium, 0.294 to 0.965% of molybdenum, and 0.508 to 2.0% of carbon with the balance being iron, and inevitable impurities, and having a micro structure wherein a bainite matrix structure or a mixed bainite and sorbite matrix structure includes a nucleus having a hard phase composed mainly of chromium carbide, and a ferrite surrounding said nucleus and having a high chromium concentration and a martensite surrounding said ferrite are dispersed.

Wear-resistant sintered alloy, and its production method

The invention provides a valve seat having a suitable degree of wear resistance, which can be produced without recourse to expensive elements represented by cobalt and at a cost lower than ever before. This valve seat is formed of a wear-resistant sintered alloy having a general composition consisting essentially of, in weight ratio, 0.736 to 9.65% of nickel, 0.736 to 2.895% of copper, 0.294 to 0.965% of molybdenum, 0.12 to 6.25% of chromium, and 0.508 to 2.0% of carbon with the balance being iron, and inevitable impurities, and having a metallic structure in which there are dispersed (1) a martensite, (2) a bainite having a nucleus of sorbite and/or upper bainite and surrounding said nucleus, (3) an austenite having a high nickel concentration, and (4) a hard phase surrounding with a ferrite having a high chromium concentration and composed mainly of a chromium carbide.

A source powder for a wear-resistant sintered material, consisting essentially of, in weight percentages, Cr: 3.0 to 6.0%, 2 Mo+W: 10.0 to 20.0%, V: 1.0 to 8.0%, Co: 10.0% or below, C: 0.20% to {0.01(2 Mo+W)+0.24 V}%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.0% and the balance being Fe and unavoidable impurities, or one prepared by adding 0.10 to 0.8% of S to the above composition. This powder can be compacted into a green compact having a high green density, which can further give a wear-resistant sintered material having a high sintered density, hardness and strength.

Source powder for wear-resistant sintered material

Disclosed is a sintered iron alloy and a method of manufacturing the same. The sintered alloy comprises: an alloy matrix and a lead phase for imparting lubricability to the sintered alloy. The alloy matrix comprises a first alloy phase being composed of 0.5 to 3% nickel by weight, 0.5 to 3% molybdenum by weight, 5.5 to 7.5% cobalt by weight, 0.6 to 1.2% carbon by weight, and the balance iron, and a second alloy phase being composed of 26 to 30% molybdenum by weight, 7 to 9% chromium by weight, 1.5 to 2.5% silicon by weight, and the balance cobalt. The content of the lead phase in the sintered alloy is not more than 3.5% by weight. The lead phase is dispersed in the alloy matrix and a pore which is formed in the alloy matrix. The ratio of the lead dispersed in the alloy matrix to the total lead phase is 60% by weight or more, and the lead phase dispersed in the alloy matrix is particles in which the maximum particle size is 10 .mu.m or less. In manufacture, a lead powder having a particle size of approximately 50 .mu.m or less is mixed a first raw material powder for the first alloy phase and a second raw material powder for the second alloy phase at a lead content of not more than 3.5% by weight. After compacting and sintering the mixture, the sintered compact is cooled so that the temperature of the compact in the vicinity of 328.degree. C. is cooled at a cooling rate of approximately 2.degree. C./min. or more.

Sintered iron alloy resistant to abrasion at high temperature and method

Disclosed is a sintered alloy composition and method of manufacturing the same, the sintered alloy composition having a multi-phase structure, comprising: a first phase composed of aluminum and copper; and a second phase being dispersed in the first phase and composed of molybdenum, chromium, silicon and cobalt. This alloy composition has excellent abrasion and corrosion resistance, preferably to be used for making machine parts such as valve seats for engines.

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Chiba, Japan

Yoshimasa Aoki