Method of improving fatigue life of cast nickel based superalloys and composition

Patent · Tue Mar 14 04:00:00 EST 1978

OSTI ID:863029

Denzine, Allen F ^[1]; Kolakowski, Thomas A ^[2]; Wallace, John F ^[3]

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1. Chardon, OH
2. Cleveland, OH
3. Shaker Heights, OH

The invention consists of a method of producing a fine equiaxed grain structure (ASTM 2-4) in cast nickel-base superalloys which increases low cycle fatigue lives without detrimental effects on stress rupture properties to temperatures as high as 1800.degree. F. These superalloys are variations of the basic nickel-chromium matrix, hardened by gamma prime [Ni.sub.3 (Al, Ti)] but with optional additions of cobalt, tungsten, molybdenum, vanadium, columbium, tantalum, boron, zirconium, carbon and hafnium. The invention grain refines these alloys to ASTM 2 to 4 increasing low cycle fatigue life by a factor of 2 to 5 (i.e. life of 700 hours would be increased to 1400 to 3500 hours for a given stress) as a result of the addition of 0.01% to 0.2% of a member of the group consisting of boron, zirconium and mixtures thereof to aid heterogeneous nucleation. The alloy is vacuum melted and heated to 250.degree.-400.degree. F. above the melting temperature, cooled to partial solidification, thus resulting in said heterogeneous nucleation and fine grains, then reheated and cast at about 50.degree.-100.degree. F. of superheat. Additions of 0.1% boron and 0.1% zirconium (optional) are the preferred nucleating agents.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• Assignee: University Patents, Inc. (Stamford, CT)
• Patent Number(s): US 4078951
• Application Number: 05/672,350
• OSTI ID: 863029
• Country of Publication: United States
• Language: English

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