Alcoa Inc.

Aluminum Company of America

Arconic Corporation

Aloca Inc.

Robert W Westerlund

Dhruba J Chakrabarti

John Liu

Gregory B Venema

Ralph R Sawtell

Jay H Goodman

Cynthia M Krist

Paul E Magnusen

Anthony Morales

Gary H Bray

Edward L Colvin

Daniel T Moulton

Anne E Zemo

Terrence N Thom

Roberto J Rioja

Diana K Denzer

Jocelyn I Petit

Joel A Bowers

Kenton P Young

Anne E Roberts

Bruce A Halter

Aluminum alloy products, such as plate, forgings and extrusions, suitable for use in making aerospace structural components like integral wing spars, ribs and webs, comprises about: 6 to 10 wt. % Zn; 1.2 to 1.9 wt. % Mg; 1.2 to 2.2 wt. % Cu, with Mg&#x2264;(Cu+0.3); and 0.05 to 0.4 wt. % Zr, the balance Al, incidental elements and impurities. Preferably, the alloy contains about 6.9 to 8.5 wt. % Zn; 1.2 to 1.7 wt. % Mg; 1.3 to 2 wt. % Cu. This alloy provides improved combinations of strength and fracture toughness in thick gauges. When artificially aged per the 3-stage method of preferred embodiments, this alloy also achieves superior SCC performance, including under seacoast conditions.

Aluminum alloy products having improved property combinations and method for artificially aging same

Aluminum alloy products, such as plate, forgings and extrusions, suitable for use in making aerospace structural components like integral wing spars, ribs and webs, comprises about: 6 to 10 wt. % Zn; 1.2 to 1.9 wt. % Mg; 1.2 to 2.2 wt. % Cu, with Mg&#x2266;(Cu+0.3); and 0.05 to 0.4 wt. % Zr, the balance Al, incidental elements and impurities. Preferably, the alloy contains about 6.9 to 8.5 wt. % Zn; 1.2 to 1.7 wt. % Mg; 1.3 to 2 wt. % Cu. This alloy provides improved combinations of strength and fracture toughness in thick gauges. When artificially aged per the 3-stage method of preferred embodiments, this alloy also achieves superior SCC performance, including under seacoast conditions.

Aluminum alloy products, such as plate, forgings and extrusions, suitable for use in making aerospace structural components like integral wing spars, ribs and webs, comprises about: 6 to 10 wt. % Zn; 1.2 to 1.9 wt. % Mg; 1.2 to 2.2 wt. % Cu, with Mg&#x2266;(Cu+0.3); and 0.05 to 0.4 wt. % Zr, the balance Al, incidental elements and impurities. Preferably, the alloy contains about 6.9 to 8.5 wt. % Zn; 1.2 to 1.7 wt. % Mg; 1.3 to 2 wt. % Cu. This alloy provides improved combinations of strength and fracture toughness in thick gauges. When artificially aged per the three stage method of preferred embodiments, this alloy also achieves superior SCC performance, including under seacoast conditions.

A process for improving 6XXX alloys, such as 6013, preferably includes heating, hot rolling, inter-rolling thermal treatment at a very high temperature such as 1020&#xb0; F. or more, again hot rolling (with or without subsequent continuous hot rolling or cold rolling or both), solution heat treating and artificial aging. The initial heating, inter-rolling, thermal treatment and solution treatment, especially the latter two, are carried out at very high temperatures such as 1030&#xb0; F. Each aforesaid hot rolling stage produces substantial metal thickness reduction. The improved sheet or plate product has a substantially reduced occurrence of reduced density features revealed in scanning electron microscope examination at 500X and exhibits improved (reduced) fatigue crack growth rate providing an advantage in aerospace applications such as fuselage skin, especially fuselage belly skin.

Process to improve 6XXX alloys by reducing altered density sites

A process for improving 6XXX alloys, such as 6013, preferably includes heating, hot rolling, inter-rolling thermal treatment at a very high temperature such as 1020&deg; F. or more, again hot rolling (with or without subsequent continuous hot rolling or cold rolling or both), solution heat treating and artificial aging. The initial heating, inter-rolling, thermal treatment and solution treatment, especially the latter two, are carried out at very high temperatures such as 1030&deg; F. Each aforesaid hot rolling stage produces substantial metal thickness reduction. The improved sheet or plate product has a substantially reduced occurrence of reduced density features revealed in scanning electron microscope examination at 500&times; and exhibits improved (reduced) fatigue crack growth rate providing an advantage in aerospace applications such as fuselage skin, especially fuselage belly skin.

The present invention is directed to highly controlled alloy composition relationship of a high purity Al&mdash;Mg&mdash;Cu alloy within the 2000 series aluminum alloys as defined by the Aluminum Association, wherein significant improvements are revealed in fracture toughness through plane strain, fracture toughness through plane stress, fatigue life, and fatigue crack growth resistance.

High toughness plate alloy for aerospace applications

Aluminum sheet products having highly anisotropic grain microstructures and highly textured crystallographic microstructures are disclosed. The products exhibit improved strength and improved resistance to fatigue crack growth, as well as other advantageous properties such as improved combinations of strength and fracture toughness. The sheet products are useful for aerospace and other applications, particularly aircraft fuselages.

Aluminum sheet products having improved fatigue crack growth resistance and methods of making same

A method is disclosed for treating an aluminum alloy product in order to impart a fine grain structure and thereby improve formability and surface finish characteristics. According to this method, the product is first heated to a first temperature high enough to dissolve soluble constituent phase particles into solid solution. The product is maintained at this first temperature long enough to dissolve a major portion of the soluble constituent phase particles. Thereafter, the product is subjected to a controlled cooling process. The product is first cooled from the first temperature, at a first rate that is rapid enough to minimize the precipitation of coarse-grained constituent phase particles, to a second temperature that is below the temperature at which such coarse-grained constituent phase particles will precipitate out. Then, the product is cooled from the second temperature, at a second rate that is within a range of about 1-300 degrees F. per hour, to a third temperature that is at least 50 degrees F. below the second temperature. After the temperature of the product has been reduced to the third temperature, the product is cold worked. After cold working, the temperature of the product is raised to a fourth temperature sufficient to cause recrystallization of the product. The product so treated will exhibit improved formability and surface characteristics, and may exhibit an average grain size of less than about 30 microns.

Method for treating an aluminum alloy product to improve formability and

A method of producing a sheet product and improved products having improved levels of toughness and fatigue crack growth resistance at good strength levels. The method comprises providing an aluminum base alloy containing 4 to 4.5% Cu, 1.2 to 1.5% Mg, 0.4 to 0.6% Mn, 0.12% max. Fe, 0.1% max. Si, the remainder aluminum, incidental elements and impurities and hot rolling the alloy, heating the alloy to above 910.degree. F. and additionally hot rolling it in a range of about 600.degree. to 900.degree. F., solution heat treating, preferably for a time of less than about 15 minutes at a solution heat treating temperature, and rapidly cooling and naturally aging. The invention products have very good combinations of strength together with high fracture toughness or low fatigue crack growth rate, or both, making them well suited for aerospace applications such as fuselage skin. The products preferably include a corrosion protecting cladding of aluminum or aluminum alloy.

Damage tolerant aluminum alloy products useful for aircraft applications

Disclosed is a method of making aluminum base alloy flat rolled product substantially free of Luder's lines after stretching, the method comprising the steps of providing a body of a lithium-containing aluminum base alloy and working the body to produce a flat rolled product prior to solution heat treating and quenching. The flat rolled product is preaged for a time and temperature which does not substantially affect mechanical properties but which permits stretching the flat rolled product without formation of Luder's lines. Thereafter, the preage flat rolled product is stretched and aged to a condition having a substantially stable level of mechanical properties.

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Bettendorf, IA, United States of America

Robert W Westerlund