US2027750A - Copper base alloy - Google Patents

Description

Patented Jan. i4, 135

ATES

COPPEI} BASE ALLOY Elmer L. Munson, Naugatuck, Conn., assignor to The American Brass Company, Waterbury,

60mm, a corporation of Connecticut No Drawing. Application October 20, 1934, Serial No. 749,276

L. Claims.

This invention relates to a copper base alloy containing copper, nickel, aluminum and beryllium.

It is one object of the invention to provide- 5 a copper base alloy that has a combination of hardness, strength, ductility and a wide heat treating temperature range not found in other copper base alloys.

The foregoing and other objects will appear 10 from the following descriptionancl appended claims.

Several copper base alloys now in commercial use may be hardened and strengthened by the heat treating process known as precipitation or age hardening treatment. Of these alloys two most important are the copper-nickel-aluminum alloy and the copper-nickel-beryllium alloy of I the following approximate compositions:

Per cent Per cent Copper 94.0 Copper 97.25 Nickel 5.0 Nickel 0.50 Aluminum 1.0 Beryllium 2.25

Alloys of the above and similar compositions have certain objectionable characteristics which discovered. For example, the copper-nickelaluminum alloy cannot be satisfactorily hardened at temperatures below about 325 (3., while my new alloy can be heat treated at temperatures as low as 250 C. and consequently at less expense. Again the copper-ruckel-beryllium alloys have a heat treating temperature range extending from about 250 C. to about 325 C. which is a rather narrow range for use by the 35 fabricating trade and is a source of trouble when the heat treating time and (or) temperature is not closely regulated. The hardness and several other mechanical property values of the copper-nickel-beryllium alloys reach a peak 40 somewhere in the neighborhood of 300 0., de-

pending up'on the amount of cold working and time of heating. If the applied heat is materially below 250 C. or materially above 325 C., the hardness and other characteristics are not 45 satisfactory for commercial usage. In other words in the heat treatment of the above described copper-nickel-aluminum alloys and copper-nickel-beryllium alloys the temperature must be closely regulated with respect to the selected 50 temperature, and similarly the time must be closely defined. My new alloy does not require such close regulation of the heat treatment because variations of fifty degrees within the heat treating temperature range do not seriously in- 55 fluence the hardness and other mechanical properties. In other words, there is a gradual increase in the mechanical property values from about 250 C. to about 550 C. About 550 0., the mechanical property values drop on? until a temperature of about 800 C. is reached, where do not appear in the new alloy which I have the metal, after quenching, is suiliciently soft to readily permit of cold working.

Many of the copper rich quaternary alloys 01 copper, nickel, aluminum and beryllium have no properties which make them'any better than the 5 more simple binary or ternary alloys, butl have discovered a narrow range of composition in which these alloys possess the desirable characteristics of the previously known alloys of these metals and which, in addition, are free 10 from several undesirable features.

The most valuable composition range is approximately Copper 913.75 to 96.75 15 Nickel 2.0 to 5.0 Aluminum 0.5 to 2.0 Beryllium 0.75 to 1.25

When the percentages of nickel, aluminum v and (or) beryllium materially exceed the maxi- 20 mum limits of these narrow ranges the alloy cannot be fabricated into sheets, wire, rods, and tubes by the usual cold working methods such as rolling and drawing.

If the nickel, aluminum and (or) beryllium contents are materially lower than the minimum limit, the resulting alloy can be cold worked commercially into wrought forms but will not develop the advantageous hardness, strength and ductility characteristic of the alloys within the specified limits.

However, when only the beryllium content is lowered, my new alloy still shows better mechanical properties than the previously mentioned commercial copper-nickel-aluminum alloy. A composition such as approximately Copper 90.25 to 97.25 Nickel 2.0 to no Aluminum 0.5 to 2.0 Beryllium 0.25 to one is of value for certain purposes.

A. preferred specific alloy for tensile strength, hardness and ductility is one comprising approximately 94.5% copper, 3.5% nickel, 1.0%

aluminum, and 1.0% beryllium.

A useful alloy which can be produced at more I moderate cost is one comprising approximately 95% copper, 3.5% nickel, 1.0% aluminum and 0.5% beryllium.

In the manufacture of my new copper base alloy the aluminum and beryllium may be added to the nickel and copper in the form of an addition alloy, such for example as one containing beryllium and aluminum in the proper proportions or as alloys of beryllium and/or aluminum with copper. The alloy is cast in chill or other molds and the ingots or shells may be hot and (or) cold rolled or drawn to the desired size and shape.

The cast ingots or shells 00 can also be extruded or forged, if desired. It, at any stage, it is desired to soften the alloys for working purposes,this may beaccomplished by heating preferably to about 800 C. (although a certain degree of softening will occur at any other temperature between approximately 550 C. and themelting point), and then rapidly cooling, preferably by an immediate quench If so desired, the new alloy can be hardened automatically while in commercial service if the operating temperature is within the wide temperature range aforementioned.

My experiments have indicated that the nickel content should exceed the sum total of the aluminum plus beryllium content to secure the maximum hardness and strength.

An important advantage of an alloy made in accordance with the present invention is that the amount of beryllium required is only about one-half the quantity necessary in the prior copper-nickel-beryllium alloy to obtain nearly as great hardness and tensile strength values. At the present time, beryllium metal is more or less rare and expensive. tion in beryllium content means that the base metal cost of the new alloy will be about 60 percent less than that of the prior alloy at current metal prices. This reduction is reflected in a lower sales price for the new alloy and consequently permits more extensive use of same in fields heretofore considered prohibitive due to the high cost of the prior copper-nickelberyllium alloy.

Another'advantage of an alloy made in accordanc'ewith the present invention is the greater softness of the annealed material in comparison with that, of the copper-nickelberyllium alloy. For example, the Rockwell hardness of my new wrought alloy after annealing at 800 C. for /2 hour followed by a quench in water is about G 12, while the Rockwell hardness of the copper-nickel beryllium alloy similarly annealed and quenched is about G 25. This increased softness of my new copper-nickel-aluminum-beryllium alloy will permit greater reductions between anneals and with somewhat less die wear when drawn into wire or tubes than is possible with the copper-nickelberyllium alloys.

Another advantage embodied in my invention is that afiorded during the casting operation by the presence of the protective aluminum film on the surface of the molten metal which helps to prevent the lossof valuable beryllium by volatilization. In the copper-nickeL-beryllium alloy some loss of the expensive element beryllium occurs by volatilizationwhen the metal is I alloys containing nickel and aluminum make my Therefore, this reduc- -1.25% beryllium, and the balance copper, in

new alloy particularly suitable for such articles as non-sparking tools, hardware, knives,

'chisels, springs, wire screens, tubes, gears, terminals, clips, bolts, nuts, coins, clock parts; jewelry, chains, valves, hinges and many. other articles. 5

Having thus set forth the nature of my invention, what I claim is:

1. An alloy composed of copper. nickel. aluminum and beryllium in proportions substantially -within the following ranges: 10

Percent Copper 91.75 to 96.75 Nickel 2.0 to 5.0 Aluminum 0.5 to 2.0 Beryllium 0.75 to 1.25 15 2. An alloy comprising approximately 94.5% copper, 3.5% nickel, 1.0% aluminum and 1.0%. beryllium.

3. A copper base alloy comprising approximatelycopper, 3.5% nickel, 1.0% aluminum and 0.5% beryllium.

4. A copper base alloy composed of copper, nickel, aluminum andberyllium in proportions substantially within the following ranges:

25 Percent Copper 90.25 to 97.25 Nickel --a 2.0 to 7.0 Aluminum 0.5. to 2.0 Beryllium 0.25to 0.75 30 5. A copper base alloy which is capable of extensive drawing, rolling and other forms of hot and cold working composed of 2.0% to 7.0% nickel; 0.5 to 2.0% aluminum; 0.25 to 1.25% beryllium, and the balance substantially copper.

6. A copper base alloy which has been hardened by heat treatment composed of 2.0% to 7.0% nickel; 0.5 to 2.0% aluminum; 0.25 to 1.25% beryllium, and the balance substantially copper, in which the nickel content exceeds the aluminum and beryllium content.

7. A copper base alloy characterized bybeing hardenable by heat treatment composed of 2.0% to 7% nickel; 0.5 to 2.0% aluminum; 0.25 to 45 which the nickel content is approximately in the ratio of 3 to'l aluminum and approximately 0.25 to 1.25% of beryllium, the balance of the 60 alloy consisting of copper, and the nickel content being about 3 times the aluminum content, to heat treatment involving heating the alloy to a temperature of the order of 800 C. followed by rapid cooling and reheating to a. 65 temperature of about 250-550 C.

10. A manufacture as set forth in claim 9, in which the alloy, after rapid cooling from the temperature of the order of 800 C. is subjected to cold working prior to reheating.

' EL'MER L. MUNSON.