US2126742A - Alloy - Google Patents

Description

Patented Aug 16, 1938 i p UNITED ALLOY Anthony G. de GoLver, New York, N. Y.

.No Drawing. Application April 17, 1936,-

Serial No. 75,020

3 Claims.

The present invention relates to a new and useful alloy and relates particularly to an alloy con taining as essential components boron, zirconium, tungsten and cobalt, which has a high degree of 5 hardness and other valuable properties.

This application is a continuation, in part, of my co-pending application, Serial No. 720,203, filed on April 12, 1934.

An object of the present invention is to pro- 10 vide an alloy especially adapted for use as metal ,cutting or forming tools, the cutting emciency of which is several times greater than that of present known high speed steels and other alloys. A further object of this invention is to provide if; an alloy which is free from, or substantially free from parbon and which is readily amenable to thermal treatment, by means of which the hard ness, tensile strength, cutting efiiciencyand other physical properties and characteristics may be 20 accurately controlled over a comparatively wide' range.

I have found through experiment that by alloying or otherwise intimately combining bron,.

zirconium, tungsten and cobalt within the range 2 boron from 0. 50% to 5%, zirconium 1.50% to 20%, tungsten to 40% and cobalt substantially the balance, that I obtain metallic compositions which possess in combination materially improved physical properties compared .to those of heretofore known alloys or compositions intended for the cutting or working of metals.

Alloys of this invention may be used in the cast condition but approximate maximum values of hardness and certain other important physical properties can be developed only through thermal treatment, or through mechanical working and subsequent thermal treatment; Bodies of the alloys which have been subiected to such treatment are particularly valuable for use as tools,

' i dies and the like for the cutting or mechanical working of metals.

Numerous metallic compositions have heretofore been proposed as improvement on the generally known 18-4-1 type of tungsten-chromium- 5 vanadium high speed tool steel, and while many of such compositions possess greater hardness than such steel, all of them have disadvantages which render them unsuitable for general application as metal cutting or i'orming tools. For

50 example, sintered or fused compositions containing principally carbides of tungsten, molybdenum or tantalum bonded with a relatively soft matrix metal have a high degree of hardness, but all of these are extremely brittle. Another disadvantage 55 is that such materials, when operated as metal cutting tools at high speed, have a tendency to crater, i. e. to be worn away by contact with hot metal chips. Cast compositions such as the type comprising principally chromium, tungsten and cobalt, require the presence of at least 1.50% car- 5 ban to qualify as metal cutting tools, and, as is well known, such alloys are not only brittle, but are so sensitive to various operating conditions as to greatly restrict the scope of usefulness. One of the greatest disadvantages of virtually all of in the heretofore suggested compositions is that none of them are responsive to thermal'treatment for regulation of physical properties, and consequently physical properties and characteristics are governed entirely by the chemical composition of the w material. I

My alloy may be used in the as-nst condition, or it may be forged and rolled'or otherwise mechanically worked. I have found that both the cast and forged material are amenable to ther- 90 .mal treatment. For exampule, castor forged bodies of this alloy may have a hardness of from 54 to 61 on the Rockwell C. scale and by subjecting the material to suitable thermal treatment, such as quenching from a temperature higher 35 than 1000 'C., the hardness may be lowered to an approximate range of from 42 to 49 Rockwell C. In this condition the bodies may be ground, shaped or formed, if desired. The alloy may subsequently be submitted to a second thermal treatment, such as heating to a temperature of less than 1000 C. for a period of from one or more hours, by which the hardness may be increased to from approximately 60 to 70 Rockwell C. In the latter condition the alloy is especially valuable for the cutting or mechanical working of a large number of metals and alloyspas well as numerous non-metallic materials. An important I property of the alloy is that virtually all of the maximum hardness, developed by thermal treatment, is retained when the alloy is subjected to elevated temperatures. e. g. such as are generated in the tip of a tool cutting metal at high speed. Another outstanding advantage is that 65 when the alloy of the present invention is used as a metal cutting tool, neither the tip nor any portion of the tool is burned or cratered by hot metal chips resulting from the cutting operation. Further hot chips do not adhere to the tool re- 50 gardless oi the speed at which it may be operated. In addition, the alloy is markedly re-.

, sistant to oxidation and corrosion at both normal and elevated temperatures. Although the alloy has a high degree of hardness. especially after thermal treatment, it is remarkably resistant to failure from sudden or repeated shock.

The more important distinctive and valuable advantages are, apparently; due to the presence of appreciable amounts of boron in the composition,

in conjunction with the other essential component elements within the percentages specified herein- 1 Although I usually prefer'to -have the alloy which is to be used as a metal cutting tool, for example composed principally of boron, zirconium, tungsten and cobalt, I have found that in many instances the tungsten may be supplanted in whole or in part by molybdenum or uranium,

\ or both. The results of my investigations indicate that alloys composed principally of boron 0.50% to 5%, zirconium 1.50% to 20%, metal from the group molybdenum and uranium to 40% and the balance cobalt, possess substantially the same valuable physical properties and characteristics as the above described composition containing only tungsten in combination with boron, zirconium and cobalt. Therefore, the alloy. of my present invention comprises boron 0.50% to-5%, zirconium 1.50% to 20%, metal selected from the group tungsten, molybdenum and uranium 10% to 40% and the balance cobalt.

Specific examples of compositions within, the

scope oi the present invention which I have found well adapted for use as metal cutting tools are the following: boron 1.40%, zirconium 7%,

tungsten 12%, cobalt balance; boron 2.30%, zirconium 3%, tungsten 14.50%, cobalt balance; boron 1.20%, zirconium 9.50%, tungsten 19%, cobalt balance; boron 2.15%, zirconium 13%, mo-

. lybclenum 12%, cobalt balance; boron 1.35%, zir

conium 3%, tungsten 4%, molybdenum 10%,

I cobalt balance.

An objective of the present invention is to proa maximum of about 0.15%, as I have found that the presence of higher percentages of this element not only tend to embrittle the alloy, but

,stituent in the nature of an eutectoid.

My investigations indicate that the preferred structure of a body of the present alloy, particularlyafter thermal treatment, comprises at least two principal constituents: one, a relatively hard intermetallic compound of boron with one or more of the other essential components; and, second, a solid solution of two or more of the essential components which has a lower degree of hardness and functions as a matrix. In some instances the structure will contain a third con- The ratio of the constituents in any particular body of the alloy may be accurately controlled and fixed over a wide range by means of thermal treatment, or mechanical working and subsequent thermal treatment.

By reason of the combined advantageous physical properties possessed by the alloy of the present invention, tools and other articles composed of this alloy may be operated emciently and economically under conditions which are impossible or uneconomical with tools or articles composed of heretofore known alloys or metallic compositions.

It will be understood that theelement vanadium may be added to the alloy of the present invention in an amount from approximately 0.25% to 2.50% but the inclusion of this element does not improve any of the physical properties.

. I claim:

1. Aprecipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 1.50% to 20%, metal from the group tungsten, molybdenum and uranium 10% to 40%, the balance cobalt.

2. A precipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 1.50% to 20%, tungsten 10% to 40%, the balance cobalt.

3. A precipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 1.50% to 20%, molybdenum 10% to 40%, the balance cobalt.

ANTHONY G. pa GOLYER.