US2192497A - Beryllium-copper alloys - Google Patents

Description

Patented Mar. 5, 1940 UNITED STATES PATENT. OFFICE BERYLLIUM-OOPPER. ALLOYS Werner Hesscnbruch, Hanan, Germany, assignor to Heraeus-Vacuumschmelze A. G., Hanan-onthe-Main, Germany, a company of Germany 4 Claims. (01. 75-159 This invention relates to beryllium-copper 1- loys, and especially to that general class of alloys in which the copper is the primary constituent,

being present in amounts usually substantially greater thanabou t 90% 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 difficulties and disadvantages .have been encountered with this general class of alloys. Some of these problems are discussed morein detail hereinafter, but it is here noted that, in general, the problems are met by the present invention by virtue of employing other metals in the alloy, in addition to the beryllium and copper. It should also be kept in mind that certain addition ingredients have al-. ready been proposed for use in copper-berryllium alloys, but that the'particular ingredients chosen in accordance 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 encountered-inthe development and use of the type of alloys here under consideration, is that it has been very dimcult to secure uniformity of characteristics, especially 'hardenability, particularly when operating scale.

Another difliculty which has been encountered in connection with the use of beryllium-copper on any appreciable commercial alloys is that when such alloys have been employed forsand castings there has been a considerable tendency toward warpage and adevelopment of objectionable surface cracks during hardening, which has seriously limited this use.-

The alloys of the present invention aid materially in overcoming these difficulties. 7

As another important object of the invention may be mentioned reduction in beryllium content, which is desirable because of the relatively high cost of beryllium, while at the same time obtaining physical and other characteristicsformity of characteristics, I have found that with beryllium-copper alloys in. rolled form, a certain type of crystal structure is a very important factor in making possible uniformity of hardening by heat treatment. More particularly, as pointed out 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 such amounts, as toavoid as far as possible a heterogeneous crystal structure incorporating beta along with the alpha crystal forms.

As mentioned in said application 107,948, a homogeneous crystal structure and high physical properties are secured by theemployment 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%. v 4

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, the former being present in an amountabout .2% and the latter in'an amount about .4%. As indicated in the prior application, certain other constituents may also be added, so long as they are not of such a nature or present in. suchamounts as to impair the desired homoheating at temperatures between 250 C. and 500 0. Between the quenching and reheating, the

alloys can also be cold worked.

With regard to the foregoing type of hardening treatment, the present invention is further of considerable benefit in making possible the attainment of substantially uniform hardness without necessitating the fine or accurate control of temperature and time of treatment, such as are required with binary beryllium-copper alloys.

As noted in application 730,727 as originally filed, improved results can also be secured by adding to beryllium-copper (the beryllium being present in an amount from a trace up to about 3 preferably not more than 2.5 certain other metals, notably silicon, silver, and to a lesser exexample, up to 2% silicon, or 5% silver. The preferred ranges given in said application for these metals are-silicon from about .5% to about 7%, silver from about .5% to about 19%, and iron from about .5% to 2%. The original disclosure of said prior application also points out that more than one of these metals maybe present, in which event they may each be present in an amount upwards of a trace, and preferably of a total content of from about .5% to about 10%. p

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 possiblegreater use of cold working between anneals, this being of advantage since it avoids the necessity for repeated and expensive annealsbetween cold working steps.-

In addition to affording 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 electrical 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 pre- 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 application 219,999 are as follows:

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 beryllium, or thereabout, when there is added, for

mentioned in application 219,999, ranges as follows should preferably be used:

Cu Balance Castings from this alloy may be hardened to a very high degree. I

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.

larly for pieces to be rolled, should preferably bekept below 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%

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

Be irom a substantial amount above a trace up to about 2.5% Y

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, it 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 to about 25'? Si .2% Co .4% Cu balance Silicon and cobalt together produce good results when the combined content of the two equals from about .1% to about 1%.

Where iron is used alone, may be as follows;

Be from a substantial amount above a trace up to about 2.5% Fe irom a substantial amount above a trace, or preferably from about .5%, up to about 2% Cu bal ance the composition If iron is used with certain other additions, for instance with silicon, the composition may beas follows:

In the last table above,'it should be noted that the combined content of silicon and iron should preferably be within from .5% to about 10%. Still further, when some other metal, for instance silver, 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% Ag from a substantial amount above a trace, and preferably from about .5%, to about 10% Cu balance In the event that silver is used in combination with other metals, such as silicon or iron,

should again be kept within about .5% to about 10%. Y i

In all tables above and also in various'of the claims, it will be understood that where the copper contentis referred to (for instance- Cu balance) it is intended to include small amounts of other ingredients and/or characteristic impurities, so lon'g asthey do not materially alter the characteristic properties of the alloys.

What I claim is:

1. An alloy composed of the following ingredients'in the proportions indicated: Be from a substantial amount above a trace up to about 2.5%

Si from a substantial amountabove a trace or about .1% to about 2% Co from about 1% to about 1% Cu balance 2. An alloy composed of the following ingredients in the proportions indicated:

3. An alloy composed of the following ingredients in the proportions indicated:

Be from a substantial amount above a trace to about 2% Si {combined content from about .1% Co 7" about 1% Cu ba1ance 4. An alloy-composedof the following ingredients in the proportions indicated:

Be from, a substantial amount above a trace .to about 2% Si- .2% Co .4% Cu balance wnam HESSENBRUCH.