US2034562A - Copper base alloys - Google Patents

Description

Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE COPPER BASE ALLOYS No Drawing. Application October 13, 1934, Serial No. 748,194

17 Claims.

This invention relates to a copper base alloy composed mainly of copper, cadmium, nickel and aluminum.

It is an object of the invention to provide a copper base alloy which is not much harder and has somewhat greater strength than copper with workability, toughness, resistance to intercrystalline attack or corrosion and other desirable characteristics and physical properties, but which, after fabrication, may be hardened and strengthened considerably, if desired, by a suitable low temperature heat treatment.

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

We have discovered that there is a range of alloyscontaining copper, cadmium. nickel and aluminum in the proportions hereinafter mentioned which have desirable characteristics and physical properties not present in other commercial copper base alloys. One very important feature of these new alloys is the great increase in hardness that may be obtained by heat treatment at low temperatures. The new alloys are hardenable at temperatures from 300 C. to 550 C., and are annealed or softened at temperatures somewhat above 700 C. For example, an alloy containing approximately 93% copper, 1% cadmium, 5% nickel and 1% aluminum that had been cold rolled from 0.500" gauge to 0.100" gauge has a Rockwell G hardness value of 53 (G scale 5" ball, 150 kg. load). After being heat treated in an electric muiile furnace for two hours at 500 C., the hardness value of this same sample is increased to 81. After the said alloy has been annealed at 850 C. for 2 hours and quenched in cold water, the G hardness value is minus 34, which, after the specimen is heat treated for 2 hours at 525 C., is raised to G 60. When considered from a numerical standpoint, this Rockwell G hardness range of minus 34 to plus 81 (115 numbers) is exceptionally wide for a non-ferrous alloy.

The tensile strength ranges from about 39,900 lbs. per sq. in. to at least 91,600 lbs. per sq. in. for the said alloy. Worthy of note is that with 91,000 lbs. tensile strength there is obtained an elongation of 10% in 2" in this hard rolled sample after low temperature precipitation heat treatment. This indicates that our new alloy has not been embrittled by the heat treating operation, which condition is found in some precipitation hardening alloys.

The great increase in hardness and tensile strength is brought about by rapidly cooling the ened by low temperature heat treatment. Be-

cause the alloy is not susceptible to softening at temperatures up to about 525 C., it is suitable for condenser tubes, parts for internal combustion engines, bearings and other uses subject to operating temperatures below 525 C. In other words it has thecharacteristic' of high resistance to creep (gradual elongation) under stress even at elevated temperatures, for instance up to about 525 C.

These new alloys that have been precipitation hardened and/or work hardened by rolling and/or drawing can be softened by-annealing at about 800 C. and quenching in cold water. The annealed or work hardened metal, whether in the form of sheet, rod, tube, et al., can be readily fabricated into the'finished product and then hardened by heat treatment at a low temperature. This (a type of heat treatable alloy) is especially suitable for such articles as nuts, bolts, nipples, valves, fittings, wire screens, coins, bushings, bellows, containers, pipes, jewelry, etc.

Another very important feature of these new alloys is the excellentresist-ance which they offer to attack by corrosion. The new alloys are almost impervious to intercrystalline attack or corrosion when exposed to steam and hot water under pressures as high as 140 lbs. per sq. in. for long periods of time. This strong resistance to corrosion was found in the alloys even when stressed up to percent of the ultimate tensile strength in a steam chamber with the steam pressure maintained at about 130 lbs. per sq. inch. They also have excellent resistance to corrosion in air at temperatures above normal.

After annealing or heat treating these new alloys, the presence of athin, brick red film was observed on the surface of the wire. This film or tarnish was also noted -on annealed wire which had been pickled in dilute sulphuric acid (1 to 10) thoroughly rinsed in water and dried in an oven at about C. This filmappears to afford some protection against intercrystalline attack or corrosion.

The new alloys possess valuable corrosion resistance properties that are especially suitable for use in steam expansion joints, condenser tubes, flexible metal hose, welds, valves, tanks and the like, and are also valuable for general structural and fabricating purposes.

Several of the alloys made in accordance with the. present invention may be hot rolled, forged, extruded, pressed, stamped, etc. at a red heat, and therefore can be fabricated into various articles at moderate expense. Many of these new alloys may also be cold rolled or drawn in accordance with the regular practice for copper base alloys. A few of the alloys in this range'will cold work satisfactorily but cannot be successfully hot worked and vice versa; some of the alloys may be hot worked successfully but will not cold work satisfactorily. The composition 'range of the alloys embodying the aforementioned advantages is as follows:

In order to obtain alloys which will hot and (or) cold work satisfactorily, it is necessary to change the composition within the above mentioned range. As the nickel and (or) aluminum content is increased, the cadmium content is decreased. For example, for an alloy containing 5 per cent nickel and 1 percent aluminum, the maximum amount of cadmium permissible for hot rolling is about 1.5 percent. An alloy with approximately 15 percent nickel and 1 percent aluminum should preferably not contain more than about of one percent cadmium. An alloy containing approximately 5 percent nickel and 2 percent aluminum should preferably not have more than about 1 percent cadmium present. It is necessary to limit the cadmium content to the degree stated in order that the alloy may be capable of extensive hot and (or) cold working. The relative nickel and aluminum content with the maximum amount of cadmium advisable in the hot workable alloys are given in the following table:

Cadmium Alumi- Copper (maximum) eke! num It is to be noted that although definite percentages have been given in these tables they are illustrative only and that intermediate percentages of Ni, Al and Cd may be used as desired,

' and in such intermediate alloys the advisable maximum Cd content will correspondingly vary. The maximum hardness in the above series of alloys, most of which are heat treatable, was obtained where the nickel content exceeded the Per cent Cadmium .01 to 1.5 Aluminum .5 to 4 Nickel 3 to 30 Copper Balance An alloy which we have found to have very desirable properties particularly for use in condenser tubes or in the presence of steam and which is also adapted for various articles as sheets, rods, wire tubes, forgings etc. comprises approximately 1% cadmium, 5% nickel, 1 to 5% aluminum and balance copper. This alloy with an aluminum content up to approximately 2% can be both hot and cold worked, and from approximately 2 to 5% aluminum it is capable of cold working.

Alloys comprising approximately 78.5% copper, 0.5% cadmium, 20% nickel and 1% aluminum; and approximately 83.25% copper, 0.75% cadmium, 15% rickel and 1% aluminum, have been found to be very desirable for use where exposed to steam or other corrosive influences, and also for articles which can be fashioned by working hot or cold and subsequently hardened by heat treatment, and particularly where a white color is desirable.

The beneficial effect of cadmium plus nickel plus aluminum on copper is very marked even when each of these three elements is in small amounts, such as from,0.01% to 0.10%, particularly as to increase in hardness, resistance to corrosion and intergranular disintegration in the presence of steam.

Our invention contemplates alloys of the nature and possessing the characteristic properties herein set forth whether or not small amounts of one or more additional elements such as tin, zinc, iron, manganese, magnesium, and (or) silicon are present. The total of the additional element or elements should be less than 2% of the alloy and preferably less than 1%.

Having thus set forth the nature of our in- I vention, what we claim is:

1. An alloy composed of copper, cadmium, nickel and aluminum in amounts substantially within the following ranges:

Percent Copper 62.0 to 99.77 Cadmium 0.01 to 3.0 Nickel 0.10 to 30.0 Aluminum 0.10 to 9.0

2. An alloy composed of copper, cadmium, nickel and aluminum in amounts substantially Within the following ranges:

Percent Copper 75.0 to 99.73 Cadmium 0.05 to 2.0 Nickel 0.11 to 20.0 Aluminum 0.11 to 3.0

3. An alloy comprising approximately 1% cadmium, 5% nickel, 1% to 5% aluminum, and balance copper.

4. An alloy comprising approximately 83.25% copper, 0.75% cadmium, 15% nickel and 1% aluminum.

5. An alloy comprising aproximately 78.5% copper, 0.5% cadmium, 20% nickel and 1% aluminum.

6. A copper base alloy characterized by being capable of hot and cold working comprising approximately 0.05% to 2.5% cadmium, 0.1% to 30% nickel, 0.1% to 3% aluminum and balance copper wherein the cadmium content is gradually reduced from 2.5% tr! 0.05% as the nickel content is increased from 0.1% to 30% and as the aluminum content is increased from 0.1% to 3%.

7. A heat treatable copper base alloy capable of being hardened by heating at temperatures from approximately 300 C. to 550 C., comprising essentially copper, cadmium, nickel and aluminum in amounts substantially within the following ranges:

Percent Copper 75.0 to 96.7 Cadmium 0.05 to 2.0 Nickel 3.0 to 20.0 Aluminum 0.5 to 2.0

8. A heat treatable copper base alloy characterized by being capable of being hardened by heating at temperatures from approximately 300 C. to 550 C., composed of 0.11 percent to 2.0 percent cadmium, from 3.0 percent to 30.0 percent nickel, from 0.5 percent to 4.0 percent aluminum, and the balance substantially copper.

9. A heat treatable copper base alloy which is characterized by being capable of being hardened by heating from approximately 300 C. to 550 C., comprising approximately 3% to 30% nickel and 1% to 9% aluminum, 0.01% to 2.5% cadmium and balance substantially copper and in which the nickel content exceeds that of the aluminum content by a ratio of about 3 to 1.

10. A heat treatable, corrosion resistant copper-cadmium-nickel-aluminum alloy character ized by being capable of being hardened at temperatures from approximately 300 C. to 550 C., in which the nickel content exceeds the aluminum content, the nickel being at least 3% and not more than 30%, the aluminum at least 0.5% and not more than 5%, the cadmium from 0.01% to 2.5%, and the balance copper.

11. An alloy characterized by being capable of being hardened by heating from approximately 300 C. to 500 C. and resistant to corrosion, comprising essential amounts of copper, cadmium,

nickel and aluminum substantially within the following ranges:

12. An alloy comprising approximately 0.01%

to 1.5% cadmium, 0.5% to 4% aluminum, 3% to 30% nickel, and balance copper.

13. A heat hardenable copper-nickel-alumihum-cadmium alloy characterized by having hardness and other desirable mechanical properties produced by heating said alloy to a temperature of from 700 C. to 900 C. followed by quenching and age hardening by prolonged heating at temperatures in the range approximately from about 300 C. to about 550 C., wherein the nickel content exceeds the aluminum content, the nickel being at least 3% and not more than 30%, the aluminum at least 0.5% and not more than 5%, the cadmium from 0.05% to 2.5% and the balance copper.

14. A heat hardenable copper-nickel-aluminum-cadmlum alloy characterized by having hardness and other desirable mechanical properties produced by heating said alloy to a temperature of from 700 C. to 900 C. followed by quenching, cold working, and/or forming and age hardening by prolonged heating at temperatures in the range approximately from about 300 C. to about 550 C., wherein the nickel content exceeds the aluminum content, the nickel being at le'ast 3% and not more than 30%, the aluminum at least 0.5% and not more than 5%, the cadmium from 0.05% to 2.5% and the balance copper.

15. In the heat treatment of the copper-cadmium-nickel-aluminum alloys containing from about 0.05% to 2.5% cadmium, from about 3.0% to 30% nickel, from about 0.5% to 5.0% aluminum, with the remainder copper, the steps which comprise heating such an alloy at temperatures above a transition point, whichlies in the neighborhood of 700 C., but below its melt ing point, quenching and age hardening by prolonged heating at temperatures in the range approximately from about 300 C. to about 550 C.

16. In the heat treatment of the copper-cadmium-nickel-aluminum alloys containing from about 0.05% to 2.5% cadmium, from about 3.0% to 30% nickel, from about 0.5% to 5.0% aluminum, with the remainder copper, the steps which comprise heating such an alloy at temperatures above a transition point, which lies in the neighborhood of 700 C., but below its melting point, quenching, cold working, and/or forming and age hardening by prolonged heating at temperatures in the range approximately from about 300 C. to about 550 C.

17. An alloy comprising 62% to 97.77% copper, 0.1% to 30% nickel, 0.01% to 9% aluminum, and sumcient cadmium within the range of 0.01% to 3% to impart to the alloy materially increased resistance to corrosion in steam and in air at temperatures above normal over the same alloy without the cadmium.

CHARLES H. DAVIS. ELMER L. MUNSON.