The Boeing Company

Rockwell International Corporation

Rockwell Scientific Licensing LLC

William H Bingel

Murray W Mahoney

Michael Calabrese

Robert A Spurling

Norman G Taylor

Christian B Fuller

Gerald S Steele

Frederick E Long

A rotatable tool for friction stir welding a workpiece and an associated apparatus and method are provided. The tool includes a first pin portion that extends from a shoulder and defines a contour surface opposite the shoulder. A second pin portion extends from the contour surface of the first pin portion. The contour surface, which mixes the material of the workpiece during welding, can increase the mixing of the material at the interface, thereby increasing the strength of the joint.

Friction stir weld tool and method

Friction stir processing (FSP) modifies the surface microstructure of metals so that thick-section metal workpieces can be bent over large angles without formation of surface cracks. A thick 2519-T8 aluminum plate (25.4 mm thick and 50.8 mm wide) was friction stir processed across the pre-tensile surface to a depth of 6.3 mm, and was then bent at room temperature over a punch with radius 38.1 mm into a v-shaped die to an 80&#xb0; bend angle. Whereas unprocessed workpieces of this type exhibited surface cracking at 31&#xb0; bend angle and failed at 40&#xb0; bend angle, no cracking was evident for the friction stir processed workpiece up to 80&#xb0; bend angle.

Thick-section metal forming via friction stir processing

The present invention provides a method to repair a void in an aluminum alloy, particularly a void resulting from an exit hole left from friction stir welding (FSW). The method includes machining the void to provide a tapered bore (34) through a parent metal, i.e., the aluminum alloy (30), providing grooves and ridges (36) on a sidewall of the tapered bore, inserting into the bore a consumable tapered plug (38) having an included angle less than, or equal to, that of the tapered bore, and rotating the plug inside the bore under an applied load to plasticize both its surface and the ridges on the parent metal tapered bore. The tapered plug is preferably attached at its proximal end to a nonconsumable heat sink (40) to remove excessive heat generated during rotation of the plug. Also, a support bracket is temporarily attached to the aluminum alloy adjacent the tapered bore to receive a distal end of the plug (38) and to react to the applied load. The plasticized material (48) at the interface between the plug and the tapered bore, upon hardening, produces a strong bond consisting of refined and recrystallized fine metal. The heat sink and the support bracket can be later trimmed away.

Method to repair voids in aluminum alloys

A method is provided for joining Be-Al alloy structural members to yield a high shear strength at the interface. Surface oxides are first removed from the Be-Al alloy members. Aluminum is then selectively etched from the bonding surfaces to allow the flow of braze alloy into high aspect ratio capillary sites. A discontinuous ceramic reinforcing material, such as Al.sub.2 O.sub.3 or SiC in particulate or whisker form, is added in small quantities to a braze foil, such as Al-Si, to create a composite at the bond interface. The braze foil and reinforcing material are sandwiched between the Be-Al alloy members, and the joint is heated to above the liquidus temperature of the braze alloy but below the melting point of aluminum. The resulting interface shear strength of the Be-Al alloy bond has been tested to an average of about 60% of the parent alloy shear strength.

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Simi Valley, CA, United States of America

William H Bingel