US4222797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of imparting a fine grain structure to aluminum alloys having precipitating constituents
Assignee: Boeing North American Inc
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Filing: 1979-07-30
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Granted: 1980-09-16
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Expires: 1999-07-30
Abstract
Abstract A method is provided for imparting a fine grain structure to aluminum alloys which have precipitating constituents. The alloy is first heated to a solid solution temperature to dissolve the precipitating constituents in the alloy. The alloy is then cooled, preferably by water quenching, to below the solution temperature and then overaged to form precipitates by heating it above the precipitation hardening temperature for the alloy but below its solution treating temperature. Strain energy is introduced into the alloy by plastically deforming it in a temperature range of 380° F. to 450° F. to reduce its cross-sectional area a total of 40% minimum, at least 25% of the reduction in area being accomplished in a single continuous deformation operation. The alloy is then subsequently held at a recrystallization temperature so that new grains are nucleated by the overaged precipitates and the development of these grains results in a fine grain structure.
Inventors
- 👤 C. Howard Hamilton
- 👤 Murray W. Mahoney
- 👤 Neil E. Paton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:41
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/04; C22F1/057; C22F1/053
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
156 words
An improvement in a method of imparting a fine grain structure to an aluminum alloy having a precipitating constituent, said method having steps of: providing an aluminum alloy having a precipitating constituent; dissolving at least some of said precipitating constituent in said alloy by heating said alloy to a solid solution temperature; cooling said alloy to a temperature below said solid solution temperature; overaging said alloy to form precipitates; plastically straining said alloy; and recrystallizing said alloy by heating it above the minimum recrystallization temperature, whereby said precipitates form nuclei for the recrystallization and controlled growth of a fine grain structure; said improvement being characterized in that said step of plastically straining said alloy comprises: heating said alloy to a temperature in the range of 380° F. to 450° F. and reducing its cross-sectional area a total of 40% minimum, at least 25% of the reduction in area being accomplished in a single continuous deformation operation.
Claim 2
Dependent Claim
156 words
An improvement in a method of imparting a fine grain structure to an aluminum alloy having a precipitating constituent, said method having steps of: providing an aluminum alloy having a precipitating constituent; dissolving at least some of said precipitating constituent in said alloy by heating said alloy to a solid solution temperature; cooling said alloy to a temperature below said solid solution temperature; overaging said alloy to form precipitates; plastically straining said alloy; and recrystallizing said alloy by heating it above the minimum recrystallization temperature, whereby said precipitates form nuclei for the recrystallization and controlled growth of a fine grain structure; said improvement being characterized in that said step of plastically straining said alloy comprises: heating said alloy to a temperature in the range of 380° F. to 450° F. and reducing its cross-sectional area a total of 40% minimum, at least 25% of the reduction in area being accomplished in a single continuous deformation operation.
Claim 3
Independent Claim
134 words
A method of imparting a fine grain structure to 7075 aluminum alloy comprising: providing 7075 aluminum alloy; heating said alloy to a solution temperature in the range of 820° F. to 930° F. to dissolve precipitating constituents in said alloy; cooling said alloy to a temperature below said solution temperature; heating said alloy to an overaging temperature in the range of 700° F. to 800° F. to overage said alloy; plastically deforming said alloy by reducing its cross-sectional area a total of 40% minimum at a temperature of 380° F. to 450° F., at least 25% of the reduction in area being accomplished in a single continuous deformation operation; and heating said alloy to a temperature in the range of 600° F. to 930° F., whereby said alloy recrystallizes into a fine grain structure.
Claim 4
Independent Claim
134 words
A method of imparting a fine grain structure to 7075 aluminum alloy comprising: providing 7075 aluminum alloy; heating said alloy to a solution temperature in the range of 820° F. to 930° F. to dissolve precipitating constituents in said alloy; cooling said alloy to a temperature below said solution temperature; heating said alloy to an overaging temperature in the range of 700° F. to 800° F. to overage said alloy; plastically deforming said alloy by reducing its cross-sectional area a total of 40% minimum at a temperature of 380° F. to 450° F., at least 25% of the reduction in area being accomplished in a single continuous deformation operation; and heating said alloy to a temperature in the range of 600° F. to 930° F., whereby said alloy recrystallizes into a fine grain structure.
References Cited (Backward Citations)
US4092181A
Cited
US4092181B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-16 | 1984-03-17 | 1984-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-16 | 1988-03-17 | 1988-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-16 | 1992-03-17 | 1992-09-16 | $7700.00 | Window Closed / Lapsed |