US2126743A

US2126743A - Boron alloy

Info

Publication number: US2126743A
Application number: US84999D
Authority: US
Inventors: Golyer Anthony G De
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-06-13
Filing date: 1936-06-13
Publication date: 1938-08-16
Anticipated expiration: 1955-08-16

Description

Patented Aug. 16, 1938 umrao STATES PATENT OFFICE I BOBON ALLOY Anthony G. de Golyer, New York, N. Y.

No Drawing.

The present invention relates to a new and useful alloy and relates particularly to an alloy containing boron, zirconium, tungsten, chromium and cobalt, which is characterized by being responsive to thermal'treatment for the improvement of physical properties. This'applicatio'n is a continuation in part of my co-pending application Serial No. 721,771, filed April 21, 1934.

An object of the present invention is to provide an alloy especially adapted for use as metal cutting or forming tools, the cutting efliciency 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 an alloy which is free from, or substantially free from carbon and which is readily amenable to thermal treatment, by means of which the hardness, tensile strength, cutting emciency and other physical properties and characteristics may be accurately controlled over a comparatively wide range.

I have found through experiment that by alloying or otherwise intimately combining boron, zirconium, tungsten, chromium and cobalt within the range of boron 0.50% to 5%, zirconium 2.00% to 20%, tungsten 1% to less than 10%, chromium 1% to 25% and cobalt substantially the balance, that I obtain metallic compositions which in combination possess 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 subjected to such treatment are particularly valuable for use as tools, dies and the like for the cutting or mechanical-working of metals.

My alloy may be used in the as-cast 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 thermal treatment. of this alloy may have a hardness of from 50 to on the Rockwell C scale and by subjecting the material to suitable thermal treatment, such as quenching from a temperature higher than 1,000 0., the hardness maybe lowered to an approximate range of from 40 to 47 Rockwell C. In this condition the bodies may be ground, shaped or formed, if desired. The alloy may sub- For example, cast or forged bodies' Application June 13, 1936, Serial No. 84,999%

sequently be submitted to a second thermal treatment, such as heating to a temperature of less than 1,000" 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 alloys, as well as numerous non-metallic materials. An important 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. Although the alloy has a high degree of hardness, especially after thermal treatment, it is remarkably resistant to failure from sudden or repeatedshock.

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.

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, chromium 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 2% to 20%, metal from the group tungsten, molybdenum and uranium 1% to less than 10%, chromium 1% to.

25%, and the balance substantially cobalt, possess substantially the same valuable physical properties and characteristics as the above described composition containing only tungsten in combination with boron, zirconium, chromium and cobalt. Therefore, the alloy of the present invention comprises boron 0.50% to 5%, zirconium 2% to 20%, metal selected from the group tungsten,

11%, and cot substantially the balance.

An objective of the present invention is to pro tended for metal cutting tools. Although 1 preier to have the alloys of this invention entirely free from carbon, in many instances I have found carbon present in the nature of an impurity incidental to manufacture. It is important to restrict the amount of carbon so present to a 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 also to retard or inhibit the desired and necessary reactions during thermal treatment. Furthermore, the presence of appreciable amounts of carbon decreases the red hardness of the alloy, 1. e. hardness at temperatures of approximately 550 C. and higher.

By reason of the fact that the elements forming the essential components of the alloy of the present invention invariably are contaminated with other elements when produced in commercial quantities, the alloys of my invention usually contain insignificant amounts of one or more elements in the nature of impurities incidental to manufacture. The amount of such impurities should be restricted to percentages which are not effective on the physical properties or characteristics of the alloy. I have found that the amount of any one of such incidental impurities should be restricted to percentages not exeeding 1%, and

' in many instanes to materially lower percentages. The presence of larger amounts of such impurities not only lowers the tensile strength and impact value of the present alloy, but greatly retards, or entirely inhibits. the desired physical reactions during thermal treatment.

My investigations indicate that the preferred structure of a body of the present alloy, particularly after thermal treatment, comprises at least two principal constituents: one, a relatively amazes zirconi 5.25%, molybdenum chromium hard intermetallic compound of boron with one or more of theother essential components; and,

second, a solid solution of two or more of the essential components which has a. lower degree of hardness andfunctions as a matrix. In some instances the structure will contain a third constituent in the nature of an eutectoid. 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 efllciently and economically under conditions which are impossible or uneconomical with tools or articles composed of heretofore known alloys ormetallic compositions.

By the term "the balance substantially all cobalt, or the balance cobalt, in the foregoing and in the following claims, I intend that the alloy of the present invention comprises boron, zirconium, metal of the group tungsten, molybdenum and uranium, and chromium within the percentage limits specified, with the remainder cobalt except for ineffective amounts of impurities which may be present incidental to manufacture.

I claim:

1. A precipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 2% to 20%, metal from the group tungsten, molybdenum and uranium 1% to less than chromium 1% to 25%, the balance cobalt.

2. A precipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 2% to tungsten 1% to less than 10%, chromium 1% to the balance cobalt.

3. A-precipitation hardened alloy consisting of boron 0.50% to 5%, zirconium 2% to 20%, molybdenum 1% to less than 10%, chromium 1% to 25%, the balance cobalt.

ANTHONY G. M: GOLYER.