Method of imparting a fine grain structure to aluminum alloys having precipitating constituents
AssigneeRockwell International Corporation
InventorsMurray W. Mahoney, C. Howard Hamilton, Neil E. Paton
Life of this patent
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Abstract
A method is provided to impart a fine grain structure to aluminum alloys which have precipitating constituents. The alloy is overaged to form coarse precipitates, and then plastically deformed at least 40%. Deformation is accomplished at a temperature and at a rate which are sufficient to retain strain energy in the alloy at the end of the deformation step. The alloy is subsequently heated at a rate of at least 0.02.degree. F..multidot.s.sup.-1 to a recrystallization temperature to form a new fine grain structure.
Claims5
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;
- said improvement being characterized in that said step of recrystallizing said alloy comprises:
- heating said alloy at a rate of at least 0.02 F..multidot.s.sup.-1 to a temperature above its minimum recrystallization temperature, whereby said precipitates form nuclei for the recrystallization and controlled growth of a fine grain structure.
A method of imparting a fine grain structure to an aluminum alloy selected from the group consisting of aluminum alloy numbers 7049, 7050, 7075, 7475, 7076, 7079, and 7178, comprising:
- providing an aluminum alloy from said group;
- heating said alloy to a solution temperature in the range of 820.degree. F. to 930.degree. F. to dissolve precipitating constituents in said alloy;
- cooling said alloy to a temperature below said solution temperarture;
- heating said alloy to an overaging temperature in the range of approximately 280.degree. F. to 820.degree. F. to overage said alloy;
- plastically deforming said alloy by reducing its cross-sectional area a minimum of 40% at a temperature and at a rate which are sufficient to retain strain energy in said alloy at the end of the deformation step;
- and
- heating said alloy at a rate of at least 0.02 F..multidot.s.sup.-1 to a temperature in the range of approximately 750.degree. F. to 930.degree. F., whereby said alloy recrystallizes into a fine grain structure.
A method of imparting a fine grain structure to an aluminum alloy selected from the group consisting of 7475 and 7075, comprising:
- providing an alloy from said group;
- heating said alloy to a solution temperature in the range of 860.degree. F. to 930.degree. F. to dissolve precipitating constituents in said alloy;
- cooling said alloy to a temperature below said solution temperature;
- heating said alloy at an overaging temperature of about 750.degree. F. for about 8 hours;
- plastically deforming said alloy by reducing its cross-sectional area about 90% at a temperature of about 390.degree. F., the deformation occurring at a sufficient rate to retain strain energy at the end of the deformation step;
- and
- heating said alloy at a rate of at least 0.02 F..multidot.s.sup.-1 to a temperature of approximately 900.degree. F., whereby said alloy recrystallizes into a fine grain structure.
A method of imparting a fine grain structure to an aluminum alloy selected from the group consisting of aluminum alloy numbers 2219, 6053, 6061, 6062, 6063, 6066, and 6151, comprising:
- providing an aluminum alloy from said group;
- heating said alloy to a solution temperature in the range of approximately 960.degree. F. to 1005.degree. 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;
- plastically deforming said alloy by reducing its cross-sectional area a minimum of 40% at a temperature and at a rate which are sufficient rate to retain strain energy in said alloy at the end of the deformation step;
- and
- heating said alloy at a rate of at least 0.02 F..multidot.s.sup.-1 to a temperature in the range of approximately 705.degree. F. to 1005.degree. F., whereby said alloy recrystallizes into a fine grain structure.
A method of imparting a fine grain structure to an aluminum alloy selected from the group consisting of aluminum alloy numbers 2014, 2018, 2020, 2024, and 4032, comprising:
- providing an aluminum alloy from said group;
- heating said alloy to a solution temperature in the range of approximately 910.degree. F. to 960.degree. 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 approximately 330.degree. F. to 910.degree. F. to overage said alloy;
- plastically deforming said alloy by reducing its cross-sectional area a minimum of 40% at a temperature and at a rate which are sufficient to retain strain energy in said alloy at the end of the deformation step;
- and
- heating said alloy at a rate of at least 0.02 F..multidot.s.sup.-1 to a temperature in the range of approximately 705.degree. F. to 960.degree. F., whereby said alloy recrystallizes into a fine grain structure.
Dependencies are inferred from the claim text.