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US3660177A
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Processing of nickel-base alloys for improved fatigue properties
Assignee: RTX Corp
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Filing: 1970-05-18
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Granted: 1972-05-02
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Expires: 1990-05-18
Abstract
Abstract The fatigue properties of the precipitation-hardened, nickelbase alloys, such as Inconel 718, Incoloy 901 and Waspaloy, are significantly improved by a thermomechanical processing technique involving the generation of an intermetallic pinning phase, such as a spheriodal eta phase or an overaged gamma prime phase, with subsequent recrystallization to provide a uniform microstructure having a grain size of ASTM 10-13 or finer.
Inventors
- 👤 Edgar E Brown
- 👤 Raymond C Boettner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:19
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
22 words
The method according to claim 1 wherein: the intermetallic pinning precipitate is a spheroidal eta phase or an overaged gamma prime phase.
Claim 2
Dependent Claim
20 words
The method according to claim 2 wherein: the intermetallic pinning precipitate has an average particle sizE of about 0.1-1 micron.
Claim 3
Independent Claim
63 words
The method of improving the fatigue resistance of the precipitation hardenable, nickel-base alloys subject to eta phase precipitation which comprises: thermomechanically processing the alloy to develop a fine spheroidal eta precipitate uniformly dispersed throughout the alloy microstructure; and subsequently recrystallizing the alloy at a temperature below the solvus temperature of the eta precipitate to provide a grain size of ASTM 10 or finer.
Claim 4
Dependent Claim
33 words
The method according to claim 4 wherein: the thermomechanical processing comprises cold working of the alloy followed by heat treatment near but below the alloy recrystallization temperature to precipitate the spheroidal eta phase.
Claim 5
Dependent Claim
28 words
The method according to claim 4 wherein: the thermomechanical processing comprises warm working the alloy near but below the alloy recrystallization temperature to precipitate the spheroidal eta phase.
Claim 6
Dependent Claim
44 words
The method according to claim 4 wherein: the thermomechanical processing comprises homogenization of the alloy and precipitation of a needle-like eta phase followed by warm working near but below the alloy recrystallization temperature to convert the needle-like eta phase to the spheroidal eta phase.
Claim 7
Independent Claim
80 words
The method of improving the fatigue resistance of the Inconel 718 and Incoloy 901 alloys which comprises: working the alloy to effect a compressive strain equivalent to at least a 30 percent reduction in thickness and heat treating the alloy at a temperature of 1,500*-1,750* F. to generate a fine spheroidal precipitate uniformly dispersed throughout the alloy microstructure; and subsequently recrystallizing the alloy at a temperature below the eta phase solvus to a grain size of ASTM 10 or finer.
Claim 8
Dependent Claim
19 words
The method according to claim 8 wherein: following recrystallization the alloy is heat treated to precipitate the hardening phase.
Claim 9
Independent Claim
73 words
The method of improving the fatigue resistance of the Inconel 718 alloy which comprises: eta phase precipitation heat treatment of the homogenized alloy at 1,650*-1,700* F. for about 4-8 hours; forging to a compressive strain equivalent to at least a 30 percent reduction in thickness at a temperature of 1,750*-1, 825* F. to form a fine spheroidal eta precipitate; and recrystallizing the alloy at a temperature of 1,725*-1,800* F. for about 1 hour.
Claim 10
Independent Claim
75 words
The method of improving the fatigue resistance of the Incoloy 901 alloy which comprises: eta phase precipitation heat treatment of the homogenized alloy at 1,650*-1,700* F. for about 4-8 hours; forging to a compressive strain equivalent to at least a 30 percent reduction in thickness at a temperature of 1,700*-1, 750* F. to form a fine spheroidal eta precipitate; and recrystallizing the alloy at a temperature of about 1,725*-1, 750* F. for about 1 hour.
References Cited (Backward Citations)
US3420716A
Cited
US3519503A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |