Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1981-10-09
1984-02-14
Rutledge, L. Dewayne
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75236, 419 12, 419 17, 419 45, B22F 316, C22F 2900
Patent
active
044314485
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to hard alloys based on refructory compounds and processes for making same. Hard alloys based on refractory compounds such as carbides, borides, nitrides, carbonitrides of transition metals can be used in the metallurgy, tool manufacture, electroengineering for the production of cutting tools, hard-alloy attachments, dies and the like.
The wide and effective use of hard alloys in numerous industries is due to a whole number of their valuable properties. The main of these properties is a high hardness (86-92 HRA units) in combination with a high wear-resistance, i.e. high resistance against wear during friction both against metals and non-metallic materials. Hard alloys are capable of retaining these properties at high temperatures as well. Especially efficient is the use of hard alloys in the machine-tool manufacture--for metal machining or cutting.
BACKGROUND OF THE INVENTION
Known in the art are, apart from initially known hard alloys of tungsten monocarbide with cobalt (binder), hard alloys, wherein a portion of tungsten carbide is replaced with titanium, tantalum, niobium carbides. The content of tungsten carbide in these alloys is usually of from 60 to 97% by mass. Hardness of these hard alloys ranges from 86 to 92 HRA units, while their ultimate bending strength is within the range of from 20 to 90 kgf/cm.sup.2.
The most high-strength are tungsten-cobalt alloys employed for cutting iron and steel. Titanium-tungsten alloys including those containing tantalum or niobium carbide are less durable but ensure a higher resistance of a cutter and are employed mainly for cutting steel under high-speed conditions.
Recently a great attention has been paid to the use of tungsten-free hard alloys due to rather scarce sources of tungsten. As a rule, the hard base of such alloys is represented by titanium carbide, while nickel doped with molybdenum serves as a binder. These alloys have a high wear-resistance in cutting steel, but due to a high brittleness they are used mainly for semi-finish and finish operations of steel machining.
However, the machine-tool manufacture persistently demands the development of new, more wear-resistant hard alloys capable of being used for machining of hardened steel at high cutting speeds.
At the present time in the industry it is necessary to machine steels of a high hardness range of from 15 to 65 HRC units. The machining of hardened steels having hardness of from 35 to 65 HRC units is accompanied by considerable difficulties. Thus, titanium-tungsten alloys are used mainly for machining of steel having hardness not over 35 HRC units. For machining of steels with a hardness above 35 HRC units these alloys are unsuitable due to an insufficient hardness thereof.
From this standpoint the most promising are mineral-ceramic materials based on alumina Al.sub.2 O.sub.3 doped with high-melting carbides possessing a high hardness--up to 94 HRA units ("Cermets", ed. by J. R. Tincklepaud and W. B. Crandall, 1962, "Inostrannaja Literatura" (Foreign Literature) Publishing House, Moscow, p. 236-279). These materials, in fact, make it possible to carry out machining of hardened steel with a hardness of up to 65 HRC units. However, these mineral-ceramic materials have a low strength (ultimate bending strength is 70 kgf/mm.sup.2) and a low thermal conductivity, wherefore these are employed in cutting tools with a sophisticated cutter shape hindering its breaking. Despite the high hardness of mineral-ceramic materials, they cannot fully replace hard alloys in machining of steels, but only complement them in certain cutting operations.
To increase hardness of hard alloys, borides of transition metals, mainly titanium diboride, have been suggested to be added.
Thus, known is a hard alloy based on titanium diboride which consists of the following components, percent by mass: Inventions, Industrial Designs and Trademarks", No. 18, published May 15, 1976, Class C 22 c 29/00).
The hard alloy having the above-specified composition is used only as an
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Borovinskaya Inna P.
Dubovitsky Fedor I.
Kustova Lidia V.
Merzhanov Alexandr G.
Rutledge L. Dewayne
Zimmerman J. J.
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