US2192496A - Beryllium-copper alloys - Google Patents

Description

Patented Mar. 5, i940 r 2 192 495 UNITED STATES'PATENT OFFICE- BERYLLIUM-COPPEB ALLOYS No Drawing. Original application March 13,

tered in the developmentanduse of the type of effectively be used to harden alloys of the general 25 alloys here under consideration, is that it has class here involved is well known. Briefly, it inbeen very difficult to secure uniformity of characcludes quenching from a temperature between teristics, especialy hardenability, particularly about 500 C. and 800 C. (for example, in the when operating on anyappreciable commercial neighborhood of 750 C.) and subsequently re- 30 scale. I heating at temperatures between 250 C. and 500 Another difliculty which has been encountered C. Between' the quenching and reheating, the alin connection with the use of beryllium-copper loys can also be cold worked. alloys is that when such alloys have been em- With regard-to the foregoing type of hardening ployed for sand castings there has been a considtreatment, the present invention ,is further of 35 ,erable tendency toward warpage and a developconsiderable benefit in making possible the atment of objectionable surface cracks during hardtainment of substantially uniform hardness with-- ening, which has seriously limited this use. The outnecessitating' the fine or accurate control of alloys of the present invention aid materially 'in temperature and time of treatment, such as are 40 overcoming these difficulties. required. with binary beryllium-copper alloys. 40 As-another important object of the invention As noted in, application 730,727 as originally may be mentioned reduction in beryllium content, filed, improved results can also be secured by addwhich is desirable because of the relatively high ing to beryllium-copper (the beryllium being cost of beryllium, while at the same time obtainpresent in an amount from a trace up to about ing physical and other characteristics which are 3%, preferably not more than. 2.5%) certain oth- 45 not only equivalent to but, in some instances, suer metals, notably silicon, silver, and to a lesser perior tothqse of binary beryllium-copper alloys extentiron. In accordance with said application or ternary or quaternary alloys as heretofore pro- 730,727 (as filed) especially good results are obposed, tained-with alloys containing even as low as 1% The present application is, in part, a continuaberyllium, or thereabout, when there is added, 50

tion of my prior applications 219,999, filed July 19, for example, up to 2% silicon,,or 5% silver. The

. 1938; 107,948, filed October 28, 1936; and 730,727, preferred ranges given in said-application for J filed June 15, 1934, this last having issued Februthese metals are: silicon from about .5% to about ary 18, 1936 as Patent No. 2,030,921. 7%, silver from about .5% to about -10%, and

Referring again to the problem of non-uniformiron} from about .5% to 2%. The origi al disity of characteristics, I have-found that withbeclosure of said prior application also points out ryllium-copper alloys in rolled form, a certain "that more than one of these metals may be prestype of crystal structure is a very important "facent; in which event they may each be present in tor inmaking possible uniformity of hardening an amount upwards of a trace, and preferablyof a total content of from about .5% to about 10%. 0 V

1939, Serial No. 261,648. plication August 22, 1939, Serial No.

Germany lane 17, 1933 3 Claiins. (Cl. -160) This invention relates to beryllium-copper alloys, and especially to that general class of alloys in which the copper is the primary constituent, being present in amounts usually substantially greater than about of the entire alloy.

'- This application is a divisional application of Serial No. 261,648 filed March 13, 1939.

Certain general properties of these alloys have been known for some time, including the high hardenability thereof, but various difiiculties and disadvantages have been encountered with this general class of alloys. are discussed more in detail hereinafter, but it is here oted that, in general, the problems are met by the present invention by virtue of employing other metals in the alloy, in addition to the beryl-- lium and copper. It should also be kept in mind that certain addition ingredients have already been proposed for use in copper-beryllium alloys, but that the particular ingredients chosen in ac.- cordance with the present invention and the proportions thereof accomplish specially improved characteristics, as will appear more fully hereinafter;

One of the problems which has been encounby heat treatment. More particularly, as pointed Some of these problems Divided and this apout in application 107,948, the crystal structure should be homogeneous, and the addition ingredients should be so chosen, and they and the beryllium content should be present in suchamounts, as to avoid as far as possible a,heterogeneous crystal structure incorporating beta along with the alpha crystal form's.

As mentioned in said application 107,948, a homogeneous crystal structureand high physical properties are secured by the employment of beryllium from a trace up to about 2%, together with either or both of cobalt or silicon in an amount aggregating from about .1% to about-1%.

Still further, as mentioned in said application 107,948, especially desirable results are attained with an alloy containing the range of beryllium above indicated, together with both silicon. and cobalt, theformer being present in an amount about .2% and the latter in an amount about .4%.

indicated in the prior applicatiomcertain other constituents may also be added, so long as they are not of such a nature or present in such amounts as to impair the desired homogeneous crystal structure.

The general type of heat treatment which may Thus, with the beryllium content kept below the preferred upper limit of 2.5%, the copper would constitute upwards of 87.5%.

Said original disclosure of application 730,727 also brings out that the use of the specified metals in addition to the beryllium and copper aids in raising the recrystallization temperature so that re-softening during heat treatment is not so likely to occur.

Furthermore, with the homogeneous character of many of the alloys of this invention it is possible to employ more cold working, and as a result the invention makes possible greater use of cold working between anneals, this being of advantage since it avoids the necessity for repeated and expensive anneals between cold working steps. I

In addition to afiording the improvements relating to crystal structure and hardenability, as is pointed out in my prior application 219,999, the specific addition metal cobalt is particularly desirable since it provides high tensile strength and also higher electrical conductivity than with certain other additions, the latter property being important when the alloy is to be used for elec-. trical contact or other similar parts, and the combination of the two properties in a single alloy being unusually advantageous. for certain purposes, such as wire required to carry a high tensile load in addition to an electric current.

For the purposes emphasized in my prior application 219,999, the following ranges are preferred:

Per cent Be from .5 to 2 Co from .1 to 1 Cu balance In most instances the beryllium should be kept within from 1% to 2%, although for special purposes (notably castings) it may be carried up to as high as 2.5%.

The ranges of ingredients providing the best results for the general purposes mentioned in ap- The cobalt additionis also particularly useful for sand castings which, with other alloys of this general type, have had a tendency to develop surface cracks during hardening treatment, the

'surface cracking being greatly reduced by the employment of cobalt. For these purposes, as is mentioned in application 219,999, ranges as follows should preferably be used:

Per cent Be 'from' 1.75 to 2.25 Co from .3 to 1 .Cu balance Castings from this alloy may be hardened to a very high degree.

As to conductivity, it is preferred to maintain the composition such that the electrical conductivity in the hardened condition equals at least 22% that of copper.

From the foregoing it will be seen that, as brought out in,my prior applications, cobalt and silicon are of outstanding importance in improving various characteristics of beryllium-copper alloys, particularly hardenability, electrical conductivity and elongation, these ends being achieved with the use of a smaller amount of beryllium than would be required in a binary alloy for an equivalent degree of hardness.

The improvement in connection with uniformity of hardenability is especially noticeable when employing silicon and/or cobalt, the combination of silicon with cobalt, as mentioned in application 107,948, being especially advantageous with respect to the homogeneity of the crystal structure and uniformity of hardenability.

The addition of iron is also of importance, especially when employed in combination with silicon.

The silver addition is particularly suitable where the alloy is to be employed for special types of electrical parts, such as electrodes.

The cobalt addition is claimed in my copending application 219,999 above referred to.

To summarize'the foregoing, it may be noted that ranges of metals given below may be employed in accordance with the invention.

Note first that the beryllium content, particularly for pieces to be rolled, should preferably be kept below about about 2.5% and most desirably between. an amount substantially greater than a trace and about 2%.

When silicon alone is used, the composition should be as follows:

Be from a substantial amount above a trace up to about 2.5%

Si from a substantial amount above a trace or about .1% to about 2% Cu balance When cobalt is used in combination with silicon, the compositionshould be within the following ranges:

Be from a substantial amount above a trace up to about 2.5%

Si from a substantial amount above a trace or about .1% to about 2% Co from about .1% to about 1% Cu balance When employing both cobalt and silicon, in is desirable that the cobalt should be present in an amount about twice that of the silicon content. For instance, the following composition is effective:

Be from a substantial amount above a trace up toabout 2.5%

Si 2% Co .4% Cu balance Silicon and cobalt together produce good results when the combined content ofthe two equals from about .1% to about 1%.

Where iron is used alone, the composition may be as follows:-

If iron is used with certain other additions, for

instance with silicon, the composition may be as follows:

B e from a substantial amount above a trace up to about 2.5%

Si from a substantial amount above a trace or about .1% to about 2% Fe from a substantial amount above a trace,

or preferably from about .5%. up to about 2% Cu. balance In the last table above, it should be noted that the combined content of siliconand iron should preferably be within from .5% to about 10%. Still further, whensome other metal, for instancesilver, is used in combination with the iron and silicon, the total of the three should be kept within about .5% to about 10%.

Where silver is employed alone, the following composition may be used:

Be from a substantial. amount above a trace.

up to about 2.5% v Ag from a substantial amount above a trac and preferably from about .5%, to about 10% Cu--- -balance of other ingredients and/or, characteristic'impurities, so long as they do not materially alter the characteristic properties of the alloys.

What I claim is: 1. An alloy composed of the following "in gredients in the proportions indicated:.

Be from a substantial amount above a trace up to about 2.5% Si irom a substantial amount above a trace or about .1% to about 2% Fe fror n a substantial amount above a trace, or preferably from about .5%, up to about 2% a Cu' balance I 2. An alloy composed of the following ingredients in the proportions indicated:

Be; from a substantial amount above a traceup to about 2.5% Si ;from.a substantial amount above a trace or about .1% to about 2% 'Fe from a substantial amount above a trace,

or preferably from about '.5%. up to about 2% OIL-"balance the combined content of the silicon and iron being between about .5% and about 10%.

3. An alloy of the beryllium-copper type containing:

Be from a substantial amount above a trace up to about 2.5%

S i 1rom a'substantial amount above a trace or about .1% to about 2% Ee from a substantial amount above a trace,

or preferably fromabout about 2% Cu -atleast 90% WERNER HESSENBRUCH.

.5%. up to