US1755555A - Manufacture of alloys of copper, nickel, and aluminum - Google Patents

Description

Patented Apr. 22, 1930 UNITED STATES PATENT OFFICE WILLIAM A. MUDGE, OF HUNTINGTON, WEST VIRGINIA, ASSIGNOR, BY MESN'E AS- SIGNMENTS, TO THE INTERNATIONAL NICKEL COMPANY, IN 0., OF YORK,

N. Y.. A CORPORATION OF DELAWARE MANUFACTURE OF ALLOYS OF COPPER, NICKEL, AND ALUMINUM No Drawing. Continuation of application Serial No. 719,088, filed June 10, 1924. This application filed March 31, 1925. Serial No. 19,730.

My invention relates to the treatment of alloys containing as their main ingredients nickel, copper and aluminum, wherein the aluminum is from about .1% to 17% (from about 2% to 7% preferred); the copper is from about 1% to 90% (preferably over 10%), and the remainder is mainly nickel the nickel preferably being over about 40% uch alloy may and usually does contain small amounts of other elements, such as iron, manganese, carbon, etc. The manganese may increase somewhat, thus, of course, correspondingly decreasing slightly the proportions of the main alloying elements.

I have discovered that an alloy of the above nature may be materially changed and improved in physical properties by proper heat treatment. While the exact physical and chemical reasons underlying this phenomenon are not known to me at present, I believe that the change in physical properties is probably due to the formation by such treatment of a compound of copper and aluminum or possibly a compound of nickel, copper and aluminum. Apparently the amount of such compound or compounds formed vary with the different compositions and the heat treatment and may account for the variations noted in the physical properties.

In a long series of experiments on heat treatment of this material, I have made the following discoveries:

If the material has been quenched from a temperature of 1500 F. and above, it will be dead soft. If such dead soft material is heated, I have found the following facts:

(a) Up to about 600 F., there will be practically no change in the physical properties.

7 (6) Between 600 F. and 1000 F., a gradual increase in desirable physical properties and hardness will result; and

(a) At a range from 1000 F to 1200 F.,

- the maximum desired properties will be developed.

By physical properties in the above statement, I mean that the proportional limit, yield point, and ultimate strength and hardness will be increased, while the elongation and reduction of area will be decreased.

The above statements apply regardless of the rate of cooling, but slow cooling from any of the temperatures above mentioned will, in general, give better physical properties than when the material is rapidly cooled from these same temperatures, as for example, by quenching in oil or water or in any other suit-able quenching medium.

If the material is heated to a temperature above 1200 F., there will be a decrease in these physical properties, and this decrease will be proportional to the increase in temperature from'1200 F. up to below 1800 F.

Also the rate of cooling will affect the desired physical properties in this case. When rapidly cooled or quenched, the desired properties will be slightly lower than when slowly cooled from the same temperatures.

Also, there is a time eifect in the heating, since extending the time of heating tends to increase the desired physical properties. For example, using dead soft material and one hours heatin at the best temperature of about 1100 5, would give semi-hard material, whether cooled slowly or rapidly; whereas, if. this heating at this same temperature on the same material was continued for eight or more hours, a hard material will be produced having physical properties considerably in excess of those produced in one hours heat treatment; and this again, whether the cooling is rapid or slow.

Continued heating at the maximum temperature of about 1100 F. for more than eight hours will slightly, but definltely, 1ncrease the physical properties regardless of the rate of cooling.

As a specific illustration of these treatments, 1 will recite the following example, the material treated being composed of about of nickel, of copper and 4% of aluminum, together with 1.02.5% of iron and manganese and 05-25% carbon as commercial substituents.

1stEmampZe.Original material whose proportional limit was 80,000 psi. was quenched after heating for one hour at 1500 R, which reduced its value to 30,000 psi. Heating at 1100 F. increased the proportional limit from 30,000 psi. to 80,000 psi. at the end of three hours. The proportional limit was further raised to 95,000 psi. at the end of'the fifth hour. Longer heating at 1500 F., or an equal period at 17 F., when followed by quenching, will reduce the proportional limit of-the original material to 20,000 psi. In this event a longer heating period at 1100 F. will be required to increase the proportional limit to 95,000 psi. In this case, all the heating was carried out at 1100" F. and followed by slow cooling in air, but similar results might have been. accomplished by rapid cooling following the same-heat treatment.

It will be noted from this example that starting with an original material of high physical properties, the heat treatment reduces these physical properties to a minimum and then raises them beyond the original values, allby heat treatment and without mechanical working.

2nd EwampZe.When this alloy has been hardened and the desired physical properties developed to a high value by the heat treatment, such as before described, it may be heated in the following ways without affecting its properties:

(a) To any temperature not to exceed 1200 F. with slow cooling;

(6) To any temperature not exceeding ]1-00 F. with quenching or quick cooling.

This discovery is important, especially in using the material in locations where it is subjected to variations in temperature conditions; as, for example, when used for steam turbine blades. The maximum temperature in turbine work is lower than the above points, and hence, the material will retain its desired physical properties under these conditions, even under wide variations of temperature. In other words, intermittent service at or below these temperatures does not materially change the characteristics of the material, if tested when cooled down.

If the material is heated above these temperatures, a decrease in the desired physical properties will result, without regard to the rate of cooling, but if the material is slowly cooled after such heating, it will have higher properties than if quenched after heating to above such temperatures.

3rd EmampZe.-If this hardened material is heated to a point. .between 1200 and 1500 F., a semi-hard material will be produced, regardless of the rate of cooling; although the slowly cooled material in this case will be slightly harder than the quenched or rapidly cooled material. If this hardened material is hea ed to above l500.F., and quenched or rapidly cooled, it will produce dead soft material; while slo ly cooling it from a temnickel, 5% copper and 4.5% of aluminum has I been varied between 20,000 psi and 63,000 psi. The same heat treatment permits a variation with an alloy containing 85% nickel, 10% copper and 4% aluminum of 20,000 psi. to 85,000 psi. The same heat treatment again permits a variation with an alloy containing nickel, 15% copper and 5% aluminum of 30,000 psi, to 120,000 psi. The same heat treatment again permits a variation with an alloy containing 65% nickel, 25% copper and 4% aluminum of 25,000 psi. to 105,000

- I have found that the optimum hardening temperature is about 1100 F., when followed by slow cooling in air, apparently re gardless of the specific chemical composition of the alloy.

The above examples ,recite the major discoveries which I have made in my heat treatment research on such alloys. -I will now describe certain other features which I have found in this research.

Either the dead soft or semi-hard alloy, when these properties have been imparted by the proper heat treatments, can be machined or fabricated with about the same ease as a similar nickel-copper alloy containing no aluminum.

If the material is hardened and has the desired physical properties to a high degree, it is machined with considerable difliculty. Therefore, anyone machining or fabricating ing this material while relatively cold and without material heating, to obtain a certain article or device, would probably desire it in soft or semi-hard condition for such treat- K ment; and thereafter the desired physical properties can be imparted by. heating at from 1000 to 1200 F., the properties increasing with the length of heating, as above described, and being preferably followed by a slow cooling to bring these properties to their highest values.

Vhere the material is worked in hot condition for sale in merchant shapes, the best practice Would probably be to roll or forge itv at a temperature between 1800 F. and about 2150 F., with ordinary slow cooling in the air. This will give a semi-hard product, without any further treatment, and if the customer desired a dead soft material,v

the material as rolled or otherwise hot worked should be quenched or quickly cooled from a temperature of 1500 F. to givea soft ma terial. v If, on the other hand, there is desired a very hard alloy possessing the desired physical properties to a high d'egree",the best practice is to allow the material to cool slowly after hot working at the above temperature and then heat the material at from 1000 to 1200 F., for several hours and allow it to cool slowly-in the air. As above pointed out,

thelonger this heating extends within certain limits, the more of the compound will be formed and the greater the physical characteristics.

While I do not know definitely the chemical or physical reasons underlying the phenomena, it seems reasonable to suppose that the hardness and other desired physical properties may be due to the gradual formation of a copper-aluminum compound or possibly a nickel-copper-aluminum compound during In both cases one-sample was tested about five minutes after cooling and another about twelve weeks after cooling. The aged samples from both the quenching and the slow cooling were found to be improved in proportional limit and hardness by from 5 to 15%.

My improved heat treatment is, of course, applicable to a nickel-copper-aluminum alloy containing .1 to 17% of aluminum, whether in the cast condition or when worked hot or cold or machined.-

The advantages of my invention result from the materially changed physical characteristics obtained by heat treatment of this alloy. The proportions of the alloy may be varied within the range stated, small percentages of other metals or metalloids may be used,.and other variations may be made without departing from my invention.

Certain species of my invention .will be described and claimed in other copending applications. In the present case, I'intend to in- *clude my broader claims to the article and method and also claims to the species where the material is heated to not over 1200 F.

with regulated cooling (slow or fast), a slow .55 cooling in the preferred form giving maximum hardness. I i

This cas is ai'continuation of Serial No." 719,088, filed June 10,1924;

1. ,In the treatment of nickel copper-aluminum alloys containing fro m 2% to 17% of aluminumand at least 15% of nickel, the steps consisting of heating the material to above 600 F. but short of melting, and

.65 allowing it to cool.

Thus, wherethe material had been of an alloy of this composition.

2. In the treatment of nickel-copper-aluminum alloys containing from 2% to 17 of aluminum and at least 15% of nickel, the

,steps consisting of heating the material to above 600 F. but short of melting, and subjectinIg it to a regulated cooling action. I

3. n the treatment of nickel-copper-aluminum alloys containing from 2% to 17% of aluminum and at least 15 of nickel, the steps-consistin of heating the material to above 1000 but short of melting, and subjecting it to regulated cooling.

4. In the treatment of nickel-copper-aluminum alloys containing from 2% to 17% of aluminum and at least 15% of nickel, the steps consistin of subjecting the material to a temperature between 1000 F. and 1200 F. and then subjecting it to a regulated cooling.

5. In the treatment of nickel-copper-aluminum alloyscontaining from 2% to 17% of aluminum and at least 15% of nickel, the steps consisting of slowly cooling the material froma temperature above 600 F. but short of melting. R

6. In the treatment-of nickel-copper-aluminum alloys containing from 2% to 17 of aluminum and at least 15% of nickel, the steps consisting of slowly cooling the mashort of melting.

terial from a temperature above 1000 F: but

.4 5 7. As a-new article of manufacture, an

alloy of nickel, copper and aluminum con- Y ta1n1ng from 2% to 17% of aluminum and at least 15% of -nickel, said alloy having a physlcal structure such as is produced by heat treatment following casting and 8. As .a new article of manufacture, an alloy of nickel, copper. and aluminum conta1n1ng from2% to 17% of aluminum and at least 15% of nickel, said alloy having a physical structure such as is produced by heat -treatment following casting and hot workingof an alloy of this composition and having a proportional limit of 80,000 psiland upwar 9. As a new article of ,manufacture, an alloy of nickel, copper and aluminum conhot working taining from 2% to 17% ofaluminum and at least 15% of nickel, said alloy having a physlcal structure such as'is produced by heatlng an alloy of this composition to about .1000 to 1200 F. and cooling the same.

10. As a new article of manufacture, an alloy of nickel, copper and aluminum containing from 2% to 17 of aluminum and at least 15% of nickel, said alloy having a phys- L ical structure such as is produced by heating an alloy of thiscomposition to about 1000 to 1200 F. and cooling the same and having a prgpportional limit of 80,000 psi. and upwar s.

my hand. A. GE

In testimony whereof I have hereunto set L