Method for fabricating monolithic aluminum structures

A method for producing a monolithic aluminum or aluminum alloy structure formed of a plurality of aluminum or aluminum alloy workpiece components, comprising:

• heating at least one of the workpiece components to a first desired maximum temperature;
• fluid quenching said at least one of the workpiece components to a desired minimum temperature;
• further heating said at least one of the workpiece components to a second desired maximum temperture below the highest temperature attained prior to fluid quenching and imparting a desired grain structure to said at least one component;
• applying a stop-off material at selected areas of opposing surfaces of the workpiece components;
• assembling said workpiece components into a stack;
• applying cold roll bonding pressure at outer surfaces of the workpiece components in said stack, said pressure being of sufficient magnitude to plastically deform the components and to bond the components together at those areas thereof where said stop-off material has not been applied;
• heating the roll bonded stack of workpiece components, said heating being at a sufficient rate and at a sufficient temperature to recrystallize the matrix around the precipitates therein;
• and
• superplastically forming at least one of the workpiece components into the desired monolithic structure.

A method of producing a monolithic aluminum or aluminum alloy structure formed of a plurality of aluminum or aluminum alloy sheets, comprising:

• heating at least one of the sheets to a desired maximum temperature;
• cooling the sheets at a controlled rate to a desired minimum temperature and imparting a desired grain structure to said at least one sheet;
• providing stop-off material at selected areas of opposing surfaces of the sheets where it is desired that the sheets not be bonded together;
• assembling said sheets into a stack;
• applying cold roll bonding pressure at outer surfaces of the sheets in said stack, said pressure being of sufficient magnitude to plastically deform the sheets and to bond the sheets together at those areas thereof where stop-off material has not been applied;
• further heating the roll bonded stack of sheets in order to recrystallize the matrix around the precipitates in the sheets and diffusion strengthen the bond;
• and
• superplastically forming at least one of the sheets into the desired monolithic structure.

A method of producing a monolithic aluminum or aluminum alloy structure formed of a plurality of heat treatable aluminum or aluminum alloy sheets, comprising:

• heating the sheets to approximately 920.degree. F.;
• fluid quenching the sheets to a desired minimum temperature immediately after said heating;
• isothermally heating the sheets at approximately 750.degree. F. for approximately 8 hours;
• isothermally heating the sheets at approximately 455.degree. F. for approximately 24 hours in order to soften the sheets;
• positioning the sheets in a stack so that the sheets have opposing surfaces;
• applying stop-off material to at least one selected areas of the opposing surfaces of the sheets in order to prevent bonding of the sheets at said area;
• cooling the sheets to approximately room temperature;
• applying a rolling pressure at ambient temperature to outer surfaces of the sheets in order to concurrently roll bond the sheets at desired portions thereof and plastically deform the sheets;
• rapidly heating the sheets to a desired maximum temperature to recrystallize the alloy in said sheets, said rapid heating being sufficient to provide a desired fine grain structure to the sheets;
• providing a tunnel between at least two of the opposing surfaces of the sheets at edge portions of the sheets for insertion of a tube therebetween, the tube providing a passageway for pressurized gas between the sheets to said area where the stop-off material has been applied;
• heating the sheets to superplastic forming temperature;
• and
• injecting pressurized gas through the tube into the area between the sheets where stop-off material has been applied, the pressurized gas being sufficient to superplastically deform and elongate at least a portion of the sheets in order to provide the desired structure.