US2067306A - Alloys - Google Patents

Description

' Patented Jan. 12, 1937 NlTED STATES PATENT OFFICE ALLOYS N 0 Drawing.

Application April 12, 1934, Serial No. 720,280. Renewed July 1, 1936 8 Claims.

My invention, which relates to stainless socalled white metal having a copper base, and has among its objects the production of alloys of this kind which may be readily worked into sheets and other forms by usual mill processes, will be best understood from the following description of several examples of the alloy compounded according to the invention, the scope of which latter will be more particularly pointed out in the appended claims.

Heretofore copper base alloys containing nickel and chromium have been employed in practice only for castings. For economic reasons it has been impractical to roll or otherwise mechanically work such prior alloys as they are brittle, difiicult to work cold, and next to impossible to work hot.

Applicant has found that workable stainless copper base alloys can be produced by compounding copper, nickel and chromium in proper proportions particularly when suitable precautions are taken to secure solution of the chromium and to prevent deleterious secondary compounds. These alloys may be readily cold and hot rolled into sheets and may be otherwise attenuated while cold or hot by usual mill processes to produce variousshapes.

The alloys, which may be compounded with or without zinc, preferably contain iron for causing the chromium to enter into solution. Ordinarily, to secure satisfactory results, at least twice as much iron as chromium should be employed, the iron, however, not exceeding about 15% of the alloy.

' The alloys also preferably contain manganese, which primarily acts as a deoxidizer and desulphurizer for the nickel, but to some extent acts to protect the chromium against oxidization. Also small amounts of titanium, say from 0.05 to about 0.3%, may be added to the melt for deoxidizingthe chromium but without retaining any substantial amount of the titanium in the resulting alloy. In general, to prevent oxidization, best results will be secured when the metals are melted under cover, preferably under a layer of sodium fluoride. Sulphur, it has been found, tends to form nickel sulphide which acts to interfere with the workability of the alloy. In the absence of protecting the chromium against oxidization the chromium when melted in or with cupronickel is likely to come off as slag or be distributed throughout the alloy in the form of an oxide. Manganese, however, has a greater aflinity for sulphur than has nickel, and manganese sulphide has no deleterious eilect on the workability of the alloy. Any excess of manganese present, within the ranges of metals hereinafter stated, enters into solution and augments the efi'ect of the nickel as a whitener of the alloy, and improves its general working properties.

Thus the manganese acts to insure good work ing properties of the alloy, and acts to insure against sulphurization of the nickel, while the iron, which is soluble in the cupro-nickel, acts to cause solution of the chromium in the cupronickel.

When desired, the tensile strength of the alloy may be increased and controlled by addition of small amounts of vanadium, say from traces up to 0.1%, this metal remaining in the alloy and 15 much improving its cold working properties and its ductility and elongation. When employed, the vanadium may be substituted for an equal part of the copper.

The amount of nickel may be varied to vary 0 I the color of the alloy. With a high nickel content of about 18% a bright, clear white metal characteristic of the color of stainless steel is secured. By decreasing the nickel content to 10% and below, alloys of warmer tones are obtained, with a suggestion of a rose or pinkish tint underlying the white, which warmer tones are desirable for architectural work. The nickel content should ordinarily not exceed approximately from 20 to 25%, as above these values the alloy becomes increasingly difiicult to work. On the other hand, the nickel content should not ordinarily be less than approximately from 4 to 5%, as below these values the alloy loses its characteristic color and ceases to be stainless.

The copper content should be relatively high, and ordinarily not less than approximately 65% of the alloy, as with lower copper values the alloy becomes increasingly brittle and difficult to work. Further, the copper content should not 40 ordinarily exceed approximately when zinc and manganese both are employed, or ordinarily exceed approximately 93% when zinc is omitted.

Further, to secure the desirable properties of the alloy within the ranges of other constituents 45 hereinafter mentioned, the sum of the copper and nickel should not ordinarily be less than approximately 80%, or when zinc is present exceed approximately 95%, or in the absence of zinc exceed approximately 97%.

It has been found that the amount of chromium ordinarily should not exceed approximately 4 to 5% as values in excess of this make the alloy difilcult to work, and ordinarily should not be less 55 than approximately 0.5% to insure that the alloy is stainless.

Although the relation between the amounts of chromium and copper does not appear to be susceptible of exact mathematical expression, it has been found that very roughly these amounts vary inversely and linearly relative to each other, that and nickel constituting substantially the balance is to say, as a general rule, to produce best results ,K the higher amounts of chromium should be employed with the lower amounts of copper, and vice versa. i

The manganese, under ordinary conditions, i should not exceed about 5% of the alloy, lest; within the range of chromium above stated, it cause the alloy to become refractory and brittle. Ordinarily to secure appreciable effects by the use of manganese at least 0.25% thereof should be present. Very roughly, the amount of man.- ganese added to the melt within the ranges of metals specified, to secure satisfactory results under ordinary conditions, should vary directly with the amount of chromium, and preferably roughly equal amounts of these metals should be added to the melt, which ordinarily will result in a preponderance of manganese in the alloy due to some of the chromium coming off in the slag. Therefore ordinarily to secure satisfactory results the amount of manganese should not be less than the amount of chromium.

Zinc, which may be employed to facilitate the soundness of the preliminary castings, may be in amount between 1 and 18%.

As a suitable method of compounding the above alloys, the copper and iron may be melted under a flux of sodium fluoride and the temperature of the melt raised to about 2600 F. To this initial melt the nickel, manganese and chromium may then be added in the formof a master alloy. After the melt is perfectly fluid and homogeneous, and just before the melt is poured, the vanadium maybe added as a vanadium-copper alloy. The zinc, if employed, may be added in the form of brass to the melt just before pouring. The titanium when employed may be incorporated in the master alloy.

As an example of satisfactory alloys according to the invention I may employ 20.2% nickel, 1.3%

chromium, 6% iron, balance substantially all copper, or the same alloys with 2.5% manganese, or 5% zinc, or both, substituted for part of the copper. Very satisfactory alloys are also secured with the chromium up to about 4% and the iron up to about 8% with the balance copper, nickel and manganese, good examples of these alloys being those having up to about 3% chromium I and up to about 6% iron.

It will be understood that small proportions of other metals than those herein mentioned may bev added to the alloy to give it special characteristics when they do not to a material extent change the hereinbefore mentioned desirable physical and chemical properties of the alloy,

and also that wide deviations may be made from the embodiments of the invention herein described without departing from the spirit of the invention.

I claim: 1, Stainless so-called white metal capable of of the alloy in respect to the other metals specifled.

2. The alloys according to claim 1 containing from a trace to 0.1% vanadium substituted for an equal part of the copper.

3. Stainless so-called white metal capable of being hot and cold rolled containing, approximately, 20.2% nickel, 1.3% chromium, 6% iron, 2.5% manganese, balance substantially all copper.

4. Stainless so-called white metal capable of being hot and cold worked containing, approximately, 65 to 93% copper and 4 to 25% nickel, the sum of the copper and nickel being between approximately 80 and 97%, 0.5 to 5% chromium, 1.5 to 5% manganese, the amount of manganese being not less than the amount of chromium, and 1 to 15% iron, but at least twice as much iron as chromium, the copper and nickel constituting substantially the balance of the alloy in respect to the other metals specified.

5. Stainless so-called white metal capable of being hot and cold worked containing, approximately, 65 to 93% copper and 4 to 25% nickel, the sum of the copper and nickel being between approximately 83 and 97%, 0.5 to 4% chromium, 2 to 8% iron, but at least twice as much iron as chromium, 0.5 to 5% manganese, the copper and nickel constituting the balance of the alloy in respect to the other metals.

6. Stainless so-called white metal capable of being" hot and cold worked containing, approximately, 65 to 93% copper and 4 to 25% nickel,

. the sum of the copper and nickel being between approximately 83 and 97%, 0.5 to 4% chromium, 2 to 8% iron, but at least twice as much iron as chromium, 0.5 to 5% manganese, the amount of manganese being not less than the amount of chromium, the copper and nickel constituting the balance of the alloy in respect'to the other metals.

7. Stainless so-called white metal capable of being hot and cold worked containing, approximately, 65 to 93% copper and 4 to 25% nickel, the sum of the copper and nickel being between approximately 86 and 97%, 0.5 to 3% chromium, 2 to 6% iron, but at leasttwice as much iron as chromium, 0.5 to 5% manganese, the copper andv nickel constituting the balance of the alloy in respect to the other metals.

8. Stainless so-called white metal capable of being hot and cold worked containing, approximately, 65 to 93% copper and 4 to 25% nickel, the sum of the copper and nickel being between approximately 86 and 97%, 0.5 to 3% chromium,

balance of the alloy in respect to the other metals.

3 RICHARD A. WILKINS.