US2121759A - Alloy - Google Patents

Description

E. F. LOWRY Julie 21, 1938.

ALLOY Original Filed Oct. 50, 1929 0 0 0000 H wm5 a2 2 6% mum mdzbni LO wQZ m5O Increasing' Co baH'.

Increasing NicKel.

INVENTOR WITNESSES:

Patented June 21, 1938 PATENT oFFios ALLOY Erwin F. Lowry, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Original application October 30, 1929, Serial No.

403,664. Divided and 1935, Serial No. 26,811

4 Claims.

The invention relates generally to improvements in cobalt, nickel alloys and the process of making them, and is a division of my copending application Serial No. 403,664, filed October 30,

An object of the invention is to provide an alloy possessing the properties of high tensile strength and high proportional (elastic) limit at high temperatures.

Another object of the invention is the provision of an alloy having high ohmic resistance and capacity to resist oxidation at high temperatures.

It is also an object of the invention to provide an alloy which is ductile and which may be readily forged.

Other objects of the invention will in part obvious and in part appear hereinafter.

The invention accordinglycomprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties, and the relation of constituents,

which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a' fuller understanding of the nature and objects of the inventiomreference should be had to the following detailed description taken in connection with the accompanying drawing, in

which the single figure shows a curve which gives the desired strength of thealloy for different proportions of the ingredients.

The alloy is a cobalt nickel base alloy comprising cobalt and nickel with the addition 01' some iron and one or more of the following titanium, tungsten, manganese, vanadium or molybdenum. The amounts of the ingredients added will be given in detail hereinafter.

. Alloys have been made containing'an aggre gate of to 95% nickel and cobalt. In these alloys desirable results were obtained with 95 to 5% nickel and from 5% to 95% cobalt, the remainder being iron and one or more of the following titanium, tungsten, manganese, vanadium and molybdenum.

While the proportions of the ingredients specifled hereinbefore have been found satisfactory, a very desirable alloy has been made with the cobalt in excess of the nickel. A suitable range is nickel from slightly below 40% to 10% and cobalt 40% to 85% plus iron and one or more of the following titanium, tungsten manganese,

this application June 15,

suitable mixture which has been prepared is as follows:

Per cent 69.2 13.2 14.4

Cobalt Nickel Iron Titanium 2.5 Aluminum, manganese; silicon .7

In making the alloy the cobalt and nickel are first melted together in some suitable furnace in a reducing or inert atmosphere. An electric furnace has been found to be satisfactory for melting the ingredients of the alloy. After the cobalt and nickel have been .melted the iron and additional ingredients are added. In adding the iron, care should be exercised'to prevent oxygen in an appreciable volume from entering the furnace.

In preparing the alloy it is good practice to add a small amount of a deoxidizer such as aluminum or magnesium to remove contained oxygen. The deoxidizer may be introduced in anysuitable manner such for example as by applying it to a silica rod and plunging it into the molten metals.

On the completion of these operations the molten alloy may be cast in permanent molds. In order to prevent oxidation of the alloy, the molds may be coated with a heavy ofl.

It has been found good practice to pour the alloy rapidly into the molds after the temperature has been somewhat lowered from that to which it has been heated to obtain good alloying. This method of introducing the metal into the'molds gives a smooth surface to the ingots which is highly desirable.

The ingot thus prepared may be forged into bars of any predetermined size depending on the purposes for which the alloy is to be utilized. Generally, .in the primary forging operation the ingot should be heated but the temperature should not exceed 1100 C. In .some instances, to meet predetermined conditions in forging operations, the temperature may be raised a little higher, for example to 1150" C.

In order to make wires from the ingot it may be forged int bars of square cross section of dimension. These bars may be readily rolled at a temperature of from 700 C. to 800 Ciinto bars having a. cross-sectional area of it" x A,. 50 These'bars may be subsequently cold rolled and swaged with frequent annealing at temperatures of .800" C. to 900 '0. into wires havin some predetermined diameter. The annealing should be carried out in a reducing or an inert 56 dies.

-ment having an oxide coat.

atmosphere such as hydrogen or nitrogen to prevent the formation of an oxide coating on the surface which would become embedded in the alloy during the rolling operations.

After a wire of say 50 mils diameter has been made, it may be drawn down to any other required diameter by drawing it through diamond the drawing procedure. Wires made from this alloy have a high ohmic resistance which adapts them for the making of filaments for thermionic tubes and the like.

In view of the strength which this alloy evidences at high temperaturea it may be used for many purposes in thermionic devices. It lends itself very well to the manufacture of thermionic tubes which are provided with a fila- This alloy will receive the oxide coat and has the strength that is desired at high temperatures.

Another important advantage of this type of alloy for the making of filaments for thermionic tubes is that when subjected to heating temperatures in the neighborhood of 1000 C. they have, when subjected to stresses, stood an elongation amounting to as much as 10% to 12% of their length before breaking. This makes unnecessary elaborate compensating devices to provide for changes in size of the filament. The following table gives the physical characteristics of a representative alloy containing 58.6% cobalt, 20.6% nickel, 17.4% iron and 2.5% titanium and If -itis drawn through a number of dies, it may be'necessary to anneal the wire during While I have described my invention in considerable detail and given numerous illustrations, it is to be. understood that the preferred embodiments described in detail should be construed as illustrative and not in a limiting sense, since numerous modifications may be made wiLhout departing from the spirit and scope of my invention, and it is desired that the claims be not interpreted in a. limiting sense.

I claim as my invention:

1. A cobalt-nickel base alloy consisting of 40% to 85% cobalt and 40% to 10% nickel aggregating from 80% -to 95% of the alloy and 20% to 5% iron and titanium, the titanium ranging from about 1% to 10%015 the alloy, the alloy having high tensile strength at high temperatures.

2. A cobalt-nickel alloy consisting of approximately 58.6% cobalt, 20.6% nickel, 17.4% iron and 2.5% titanium plus .9% impurities.

3. A cobalt-nickel base alloy consisting of cobalt and nickel in the aggregate amount of 80% to 95% by weight of the alloy, the cobalt ranging from to 85% by weight and from 20% to 5% by weight iron and one of the following,

titanium, manganese or vanadium, the metal selected from the group being from 1% to 10% of the alloy.

4. A cobalt-nickel base alloy consisting of cobalt and nickel in the aggregate amount of 80% to 90% of the alloy, the cobalt ranging from 40% to and the nickel 15% to 40% and the balance being 20% to 5% iron and one or more of titanium, manganese, vanadium, the metal or nnwm F. LOWRY.

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