US3519418A - Age-hardenable nickel-base brazing alloy - Google Patents

Description

United States Patent 3,519,418 AGE-HARDENABLE NICKEL-BASE BRAZING ALLOY Paul R. Mobley and Reed E. Yount, Cincinnati, Ohio,

:issignors to the United States of America as represented by the Secretary of the Air Force No Drawing. Filed Apr. 22, 1968, Ser. No. 723,232 Int. Cl. C22c 19/00 US. Cl. 75-170 Claims ABSTRACT OF THE DISCLOSURE Age-hardenable nickel-base brazing alloys are provided which possess strength and oxidation resistance in the 1700 F. to 1900 F. temperature range. The alloys. contain as essential ingredients 3 to percent silicon, 2 to 4 percent titanium, 1 to 3 percent aluminum, 1 to 20 percent of at least one of the alloying elements selected from the group consisting of chromium, cobalt, boron and iron, and the balance being nickel accompanied by unavoidable impurities.

BACKGROUND OF THE INVENTION ice with the necessary elevated temperature strength and oxidation resistance needed for use in the fabrication of structural components subjected to the stress and strain of high temperature operational conditions. The alloys contain nickel, silicon, titanium and aluminum as essential ingredients, together with one or more alloying ingredients selected from the group consisting of chromium, cobalt, boron and iron.

Accordingly, it is the primary object of the present invention to provide age-hardenable nickel-base brazing alloys having improved combinations of high strength and high oxidation resistance at elevated temperatures.

Another object of the present invention is to provide improved nickel-base alloys of specially controlled compositions which exhibit high strength and oxidation resistance at elevated temperatures in the range of 1700 F. to 1900 F.

Other objects and advantages of the invention will become apparent from the following detailed description thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Pursuant to the above objects, the present invention contemplates a nickel-base brazing alloy containing about 3% to about 10% silicon, about 2% to 4% titanium, about 1% to about 3% aluminum, 1% to 20% of at least one of the alloying ingredients selected from the group consisting at chromium, cobalt, boron and iron, and the balance essentially nickel accompanied by unavoidable impurities. These alloys are characterized by a very high combination of strength and oxidation resistance at temperatures from about 1700 F. to 1900 F.

Typical alloys prepared in accordance with the invention are presented in Table I, while Table II presents hardness data for the alloys described in Table I.

TABLE I.-ALLOY CONSTITUENTS IN PERCENT BY WEIGHT Alloy N0 Ni 01' Co Si Fe B Ti Al teng ii l prior art nickel-base alloys, although possessing satisfac- TABLE H HARDNESS DATA (Re) tory strength properties, are characterized by an unsatisfactorily low oxidation resistance, especially at elevated Alloy 3%? f??? i fii temperature. No. Asbrazed 24 Ill 16 hrs. 4 hrs. Designers of equipment for use at high stress and ele- 1 520 5 525 620 vated temperatures require that nickel-base alloys possess 50.8 50. 5 50.8 45.0 a yield strength representing a high proportion of the 32:2 ggg 28:2 2%? tensile strength thereof since the yield strength is the 53.5 property of the alloy employed by the designer. Also, 2 age-hardenable nickel-base alloys having improved oxida- 58:5 57:0 58:0 56:0 tion resistance in combination with improved strength gig properties are required by the art for use at elevated tern- 56.0 peratures. Although attempts have been made to overcome 3 22:2 22:2 the aforementioned difficulties, none have been entirely 52.5 54.5 53.0 53.4 successful when carried into practice on a commercial 4 gig 3 gig basis. In further attempts to overcome the difficulties of 60 56.0 53.5 57.5 54.8 the prior art, however, it has been discoverd that age- 25 g hardenable nickel-base alloys containing specially con- 54.3 trolled and coordinated amounts of alloying elements possess an improved and outstanding combination of high The alloys may be prepared by conventional techniques strength and oxidation resistance in the temperature range h as HOB-Consumable electrode melting under a Partial from about 1700 F. to about 1900 F, argon atmosphere with the heat source a "FIG welding torch oscillated over the charge. The alloys may also be SUMMARY OF THE [INVENTION produced by other conventional methods where a con- In accordance with this invention novel age-hardenable trolled atmosphere is used. For example, in preparing a nickel-base alloys are formulated from an admixture of desired brazing alloy, the ingredients are charged, in

specially controlled amounts of certain alloying ingredicuts. The combination of ingredients provide the alloys weighed increments, into an arc melting furnace which may comprise a water-cooled copper crucible and a tungsten electrode. The charge is melted under an inert atmosphere such as argon or helium to prevent contamination of the melt. The resulting melt is then solidified into an ingot. These alloys can be comminuted into small chunks or to a powder as desired. In its powder condition, the alloys can be uniformly mixed with a binder such as nitrocellulose or an acrylic resin to form a paste, it being essential that the binder burn away leaving no ash to contaminate the brazed joint.

In whatever form prepared, the braze material is placed about the surfaces to be joined. The furnace used should be capable of reaching a temperature of about 2500 F. For example, the joint and surrounding braze material may be heated by a radio frequency induction heater to above the liquidus of the brazing alloy and held at temperature until the melted alloy is observed to melt and flow freely over the surfaces to be joined. At this point the heating means is switched off and the melted alloy allowed to freeze to form the brazed joint.

Brazed T joints have been made successfully in accordance with this procedure and with the alloys within the scope of the invention. All were brazed at approximately 2050 C.

Unless otherwise indicated, the term percent, -as used in the instant specification and appended claims, refers to percent by weight based on the total alloy weight.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will readily understand that various modifications and alterations may be resorted to without departing from the spirit of the invention and that all such modifications as fall within the scope of the appended claims are intended to be included therein.

We claim:

1. A nickel-base brazing alloy consisting essentially of about 3 to percent silicon, 2 to 4 percent titanium,

1 to 3 percent aluminum, 1 to 20 percent of at least one of the alloying elements selected from the group consisting of chromium, cobalt, boron and iron; and the balance being nickel accompanied by unavoidable impurities.

2. A nickel-base brazing alloy in accordance with claim 1 consisting essentially of about 5 percent silicon, 3 percent titanium, 2 percent aluminum, 7 percent chromium, 2 percent iron, 2.9 percent boron, and the balance being nickel accompanied by unavoidable impurities.

3. A nickel-base brazing alloy in accordance with claim 1 consisting essentially of about 3.5 percent silicon, 3 percent titanium, 2 percent aluminum, 1.9 percent boron and the balance being nickel accompanied by unavoidable impurities.

4. A nickel-base brazing alloy in accordance with claim 1 consisting essentially of about 4.5 percent silicon, 3 percent titanium, 2 percent aluminum, 3.3 percent boron, 18 percent cobalt and the balance being nickel accompanied by unavoidable impurities.

5. A nickel-base brazing alloy in accordance with claim 1 consisting essentially of about 10 percent silicon, 3 percent titanium, 2 percent aluminum, 17 percent chromium and the balance being nickel accompanied by unavoidable impurities.

References Cited UNITED STATES PATENTS RICHARD O. DEAN, Primary Examiner US. Cl. X.R.