Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1992-11-10
1995-04-04
Mai, Ngoclan T.
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75240, 75246, 75252, 419 14, 419 17, 419 38, 419 47, C22C 2900
Patent
active
054033713
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an iron-based powder for making wear-resisting and heat-resisting components by compacting end sintering.
The invention also relates to a component which is powder-metallurgically made of the inventive powder. Finally, the invention also relates to a method of powder-metallurgically making such a component.
A well-known material in wear-resisting and heat-resisting components is the so-called high-speed steel. This is characterised by relatively high contents of alloying materials which above all are carbide-forming elements, i.e. provide wear resistance but also increase the hardenability and high-temperature strength of the component. Normal alloying materials in high-speed steel are Cr, Mo, W and V, but also Co and a number of other substances can be used.
In order to achieve the purpose of high-speed steel, i.e. a powder-metallurgical material which is as hard, wear-resisting and heat-resisting as possible, a liquid phase sintering is performed after the powder has been compacted into the desired shape, whereby the component attains a high density.
The high-speed steel powder itself is usually made by water atomisation. The carbon content is selected so that a subsequent soft annealing results in a powder in which the carbon in mainly bound in the form of carbides. To give the powder a desired compressibilty, a low content of dissolved carbon is kept in the matrix.
By today's technique, a high density of the sintered component is attained in that the sintering is carried out at 1250.degree.-1300.degree. C. and the content of C is kept in a narrow range. Generally use is made of vacuum sintering, but sintering in reducing atmosphere with a low dew point is also applied. The sintering is carried out at these temperatures in order to provide sufficient liquid phase and thus cause shrinkage to the required high density.
The using of prior art combinations of alloying materials implies that the manufacture of a finished component, all the way from annealing to sintering, is complicated and expensive. Thus, the sintering temperature and carbon content must be carefully controlled to attain a sufficiently high density in the sintered material. The sintering temperatures used also render it impossible to perform the sintering in a belt furnace in which sintering temperatures above 1150.degree. C. normally cannot be achieved.
The object of the present invention therefore is to provide an iron-based powder which allows simple and relatively inexpensive manufacture of wear-resisting and heat-resisting components by compacting and sintering.
In particular, it should be possible to perform the sintering operation in a belt furnace, i.e. at lower temperatures than about 1150.degree. C.
According to the invention, this object is achieved in that the iron-based powder contains, in addition to Fe, 3-15% by weight of Mo and/or 3-20% by weight of W, the total amount of Mo+W being in the range of 3-20% by weight; 0.2-1.0% by weight of P; 0.5-1.5% by weight of C, and less than 3.0% by weight of other substances.
Preferably, the powder contains no, or just a small amount of Cr and V which are sensitive to oxidation. The maximum total amount of Cr and/or V should be less than 2% by weight, preferably less than 1% by weight.
In a preferred composition, the powder contains 0.7-1.3% by weight of C, suitably however at least the amount which is required to form carbides with an included amount of Mo and W. Further, P can be included in the form of a phosphorous compound, suitably an iron phosphide, most preferably Fe.sub.3 P. Finally, the amount of Mo can be 5-14% by weight, the amount of W 5-16% by weight, and the total amount of Mo+W should be in the range of 5-16% by weight.
Owing to the amount of P included, it has appeared that the inventive powder can be liquid phase sintered at the temperatures which are normally used for sintering in a belt furnace. The sintered material also has properties similar to those of high-speed steel, despite complete or substantially complete absence of Cr and,
REFERENCES:
patent: 3698055 (1972-10-01), Holtz, Jr. et al.
patent: 3856479 (1974-12-01), Iwata et al.
patent: 3918923 (1975-11-01), Inoue
patent: 3977838 (1976-08-01), Hachimoto et al.
patent: 4128420 (1978-12-01), Esper et al.
patent: 4388114 (1983-06-01), Suganuma et al.
patent: 4612048 (1986-09-01), German et al.
patent: 4696696 (1987-09-01), Fujita et al.
patent: 4743425 (1988-05-01), Ohsaki et al.
patent: 4767456 (1988-08-01), Spitzer
patent: 4964908 (1990-10-01), Greetham
patent: 4966626 (1990-10-01), Fujiki et al.
International Search Report for PCT/SE91/00331 corresponds to present application.
Engdahl Per
Johansson Ralf
Spasic Dragan
Hoganas AB
Mai Ngoclan T.
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