US3303022A

US3303022A - Carbon and columbium containing nickel alloys

Info

Publication number: US3303022A
Application number: US292493A
Authority: US
Inventors: Herbert L Eiselstein; Gadbut John
Original assignee: International Nickel Co Inc
Current assignee: Huntington Alloys Corp
Priority date: 1963-07-02
Filing date: 1963-07-02
Publication date: 1967-02-07
Anticipated expiration: 1984-02-07
Also published as: BE650026A; DE1225394B; GB1000963A; CH417120A

Description

United States Patent C) 3,303,022 CARBON AND COLUMBIUM CONTAINING NICKEL ALLOYS Herbert L. Eiselstein and John Gadbut, Huntington,

W. Va., assignors to The International Nickel Company, Inc, New York, N.Y., a corporation of Delaware N Drawing. Filed July 2, 1963, Ser. No. 292,493 6 Claims. (Cl. 75-170) The present invention relates to high-nickel alloys and, more particularly, to high-nickel alloys having an improved combination of properties, including strength and conductivity.

Heretofore, the art has endeavored to provide alloys for use in many fields, such as in nuclear pOWer plants, rocket engines, aircraft engine fuel and oil coolers, compact heat exchangers and the like, which would have satisfactory strength in the annealed condition while still retaining a high heat conductivity. Pure copper has excellent heat conductivity but in the annealed condition the strength of this metal is so low it is not of practical engineering interest for such uses. Highly pure nickel (99.97% nickel) has a coefficient of heat conductivity of about 600 B.t.u./hr./ft. /in./ F., and a yield strength in the annealed condition of only about 14,000 pounds per square inch (p.s.i.). Commercial Wrought nickel (99.5% nickel) has a coeflicient of heat conductivity of about 400 B.t.u./hr./ft. /in./ F. and a yield strength in the annealed condition of about 20,000 p.s.i. Various alloys of nickel and copper, e.g., 70:30 cupronickel, find considerable engineering usage. While 70:30 cupronickel has a yield strength of about 18,000 p.s.i. in the annealed condition, the coefficient of heat conductivity is only about 200 B.t.u./hr./ft. /in./ F. Various nickel-chromium alloys, e.g., an alloy containing about 80% nickel, about 14% chromium, and about 6% iron, have a-greatly improved yield strength on the order of about 30,000 p.s.i. in the annealed condition but such alloys have poor conductivity such that the coefficient of heat conductivity is only about 100 B.t.u./hr./ft. /in./ F. A need has accordingly existed in the art for an alloy which would have substantially improved strength in the annealed condition but which would still have a coefiicient of heat conductivity approaching that of pure nickel. Although attempts were made to overcome the foregoing difiiculties, none, as far as we are aware, was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that a special high-nickel alloy has a markedly improved yield strength in the annealed condition as compared to nickel of commercial purity While retaining to a marked extent the heat conductivity of nickel.

It is an object of the present invention to provide a high-nickel alloy having an improved combination of properties.

Another object of the invention is to provide a highnickel alloy having improved strength as compared to pure nickel and commercially available nickel alloys.

The invention also contemplates providing a highnickel alloy having improved strength while retaining to a marked extent the conductivity of nickel.

It is a further object of the invention to provide a highnickel alloy useful for the production of articles such as condenser and heat-exchanger tubing, which articles have adequate strength and satisfactory heat conductivity.

Other objects and advantages will become apparent from the following description.

Generally speaking, the present invention contemplates providing a high-nickel alloy containing at least about 1% but not more than about 7.5% columbium, about 3,303,022 Patented Feb. 7, 1957 ice 0.07% to about 1% carbon, e.g., about 0.1% to about 1% carbon, with the ratio of columbium content to carbon content being about 6:1 to about 25:1, and with the balance of the alloy, except for minor amounts of incidental elements and impurities not exceeding a total of about 1.75%, being essentially nickel. The alloys are characterized by a yield strength in the fully annealed conditionot at least about 27,000 p.s.i. and by a coefficient of heat conductivity of at least about 300 B.t.u./ hr./ft. /in./ F.

In carrying the invention into practice, it is advantageous to employ alloys containing about 1.2% or 1.4% to about 3.5% columbium, about 0.2% to about 0.4% carbon, with the ratio of columbium content to carbon content being about 6:1 to about 15:1, and the balance, except for minor amounts of incidental elements and impurities not exceeding about 1.75%, being essentially nickel. Even more advantageously, the columbium to carbon ratio is at least about 7: 1. These alloys are characterized by a yield strength in the annealed condition of at least about 40,000 p.s.i. and by a thermal conductivity coefficient of at least about 300 B.t.u./hr./ft. in./ F.

The ranges of columbium content and carbon content and the ratio of columbium content to carbon content as set forth hereinbefore are all important and these requirements must all be met in order to obtain the combinations of strength and conductivity contemplated in the special nickel alloys provided in accordance with the invention. When any of these requirements is not met, the properties of the resulting alloys are unsatisfactory from the standpoints of strength and/or conductivity. In addition, when the columbium to carbon ratio is less than 6:1 there is a detrimental tendency toward the formation of graphite in the resulting alloy. For example, an alloy containing 0.20% carbon, 1.15% columbium, 0.5% iron, 0.27% manganese, 0.01% titanium, 0.048% magnesium, 0.029% zirconium, balance nickel, and having a columbium to carbon ratio of 5.75 developed graphite after a 1600" F. anneal and had a comparatively low room temperature yield strength of 29,300 p.s.i. with a thermal conductivity of 334 whereas comparable Alloy 3, containing 0.24% carbon and having a columbium to carbon ratio of 7.25, developed no graphite and had a yield strength of 56,300 p.s.i. under the same conditions. Furthermore, alloys containing carbon contents less than 0.07% 'develop unsatisfactory strength. Thus, an alloy containing 0.04% carbon, 0.03% manganese, 0.66% iron, 0.33% titanium, 1.63 columbium, balance nickel, when tested at room temperature, had a low yield strength of 20,600 p.s.i. (0.2% ofi set), a tensile strength of 76,200 p.s.i., an elongation of 60%, a reduction in area of and a thermal conductivity of 316. Zirconium has a strengthening effect in the alloy and may be employed in amounts up to about 0.1%. The alloy may contain incidental elements and impurities such as up to about 1.25% iron, up to about 1% titanium, up to about 1% manganese, up to about 0.1% silicon, up to about 0.2% copper, and minor amounts of residual deoxidizers such as mangnesium, calcium, cerium, aluminum, etc., in a total amount not exceeding about 0.1%. Elements such as chromium, molybdenum, tungsten and vanadium are detrimental impurities and should be substantially absent from the alloy, i.e., should not be present in amounts exceeding a total of about 0.5 Other detrimental impurities such as sulfur, phosphorus and lead should be limited to a maximum of about 0.01% sulfur, about 0.01% phosphorus, and about 0.001% lead. Incidental elements and impurities reduce the conductivity of the alloy without appreciable increase in the strength thereof and should not be present in total amounts exceeding 3 about 1.75% and preferably should not be present in amounts exceeding about 0.5%.

A series of alloys in accordance with the invention were prepared by air melting the constituents in an induction furnace. The molten metal in each case was cast into ingots which were then forged into bars. The chemical composition of the melts is set forth in the following Table I:

resistance welding, etc., may be employed in joining parts made of the alloys provided in accordance with this invention.

Thermal conductivity values reported herein for alloys within the invention were determined in accordance with the method described by Morris E. Fine in Transactions A.I.M.E., volume 188, July 1950, pages 951 and 952.

Although the present invention has been described in TABLE I Alloy N 0. Percent Percent Percent Percent Percent Percent Percent Percent Percent Fe Mn Ti Mg Zr Ob/C Ni 0.28 0. 12 0. 01 0. 03 0. 040 0. 01 3. 05 I 10. 9 13:11. 0. 1. 11 0.30 0. 02 0. 024 0. 043 3. 12 12. 5 Hal. 0. 24 0. 68 0. 26 0. 01 0. 022 0. 041 1. 74 7. 25 Bal. 0. 32 0. 06 0. 25 0. 03 0. 043 0. 038 2. 87 8. 07 Bal. 0.26 O. 87 0.30 0. 02 0. 043 0. 036 2. 28 8. 8 Bal. 0. 17 0. 84 0.29 0. 03 0. 025 0. 028 2. 22 '13. 0 Bal. 0. 87 0. 05 0. 19 0. 05 7. 29 8. 4 Bal. 0. 1.11 0.29 0.02 0. 026 0.021 3.10 8. 9 Bal. 0. 07 0. 10 0. 01 0. 42 0. 046 0. 01 1. 52 21. 8 B211. 0. 08 0. 74 0. 01 0, 44 0. 061 0. 01 1, 61 20. 1 Bal.

NOTE.Ihese melts contained about 0.01% to 0.10% silicon, about 0.02% to 0.03% copper, and about 0.002%

to 0.006% sulfur.

Portions from the forged bars were annealed at 1600 F. for /2 hour. The annealed bars were subjected to tensile tests at room temperature and the thermal conductivity was established. Results ,of the tests are set forth in the following Table II:

conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as .those skilled in the art will readily understand. Such modifications and variations are considered to be Alloys in accordance with the invention are thermally stable. Thus, annealed alloys do not increase in hardness or strength when subjected to heat treatments designed to reveal age hardening, i.e., 16-hour heat treatments at a temperature in the range of 900 F. to 1600 F.

The alloys provided in accordance with the present invention are particularly applicable to the manufacture of heat exchangers which are required to have high heat transfer rates, e.g., where the overall heat transfer coeificient is at least about 1000 B.t.u./hr./ft. F. Examples of such devices include regeneratively cooled rocket thrust chambers, nuclear power plants, and heat exchangers in which boiling takes place, in-pile test thimbles, aircraft air conditioning equipment, jet engine fuel coolers and oil coolers, etc. The alloys are particularly advantageous for the manufacture of heat exchange elements having protruding surfaces, such as finned tubes and the like, as it is found that the heat transfer characteristics of such elements are significantly improved through the use therein of the alloys within the scope of this invention.

Alloys provided in accordance with the present invention may readily be joined with any of the common brazing and welding techniques. Thus, the usual brazing methods employed for joining nickel alloys and the usual welding methods which include arc welding, oxyacetylene welding, spot welding, submerged arc welding,

within the purview and scope of the invention and appended claims.

We claim:

1. A nickel-base alloy consisting essentially of about 0.07% to about 1% carbon, at least about 1% to about 7.5% columbium, with the ratio of columbium content to carbon content being about 6:1 to about 25:1, and

with the balance of the alloy, except for minor amounts of incidental elements and impurities not exceeding a total of about 1.75%, being essentially nickel.

2. The alloy according to claim 1 wherein the carbon content is at least about 0.1%.

3. A nickel-base alloy consisting essentially of about 0.2% to 0.4% carbon, about 1.2% to about 3.5% columbium, with the ratio of columbium content to carbon content being about 6:1 to about 15:1, and with the balance of the alloy, except for minor amounts of incidental elements and impurities not exceeding a total of about 1.75%, being essentially nickel.

4. The alloy according to claim 3 wherein the columbiurn content is at least about 1.4%.

5. The alloy according to claim 4 wherein the ratio of columbium content to carbon content is at least about 7: 1. i

6. As a new article of manufacture, a heat exchanger comprised of the alloy defined in claim 1.

(References on following page) References Cited 1ay the Examiner 652,061 10/1937 Gergany.

UNITED STATES PATENTS 614,349 12/1948 Great Britain. 1,355,532 V1920 Brace DAVID L. RECK, Primary Examiner. 5 WINSTON A. DOUGLAS, Examiner. FOREIGN PATENTS c. M. SCHUTZMAN, R. o. DEAN,

616,858 8/1935 Germany. Assistant Examiners.

Claims

1. A NICKEL-BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT 0.07% TO ABOUT 1% CARBON, AT LEAST ABOUT 1% TO ABOUT 7. 5% COLUMBIUM, WITH THE RATIO OF COLUMBIUM CONTENT T0 CARBON CONTENT BEING ABOUT 6:1 TO ABOUT 25:1, AND WITH THE BALANCE OF THE ALLOY, EXCEPT FOR MINOR AMOUNTS OF INCIDENTAL ELEMENTS AND IMPURITIES NOT EXCEEDING A TOTAL OF ABOUT 1.75%, BEING ESSENTIALLY NICKEL.