Ut-Battelle, Inc.

Yong Chae Lim

Zhili Feng

Michael P Brady

Ji Heon Jun

Jian Chen

Xin Sun

Richard W Davies

A fastener for use in joining dissimilar materials manufactured by the process of producing the fastener with an external surface that forms an electrically insulating oxide layer when subjected to oxidation and, after manufacture and prior to use, subjecting the fastener to a pre-oxidation process to grow the desired oxide layer in situ on the external surface of the fastener. The present invention also provides a dissimilar material joint in which the pre-oxidized fastener is used to mechanically join dissimilar materials with the oxide layer electrically insulating the fastener from at least one of the dissimilar materials. The fastener may be a rivet used in friction self-piercing riveting (F-SPR). The fastener may be fabricated from an alloy capable of forming AlOor CrOby thermal oxidation. The fastener may be pre-coated with Al or Cr that functions as a seed layer to form AlOor CrO.

Fastener joint and associated method for avoiding corrosion of dissimilar material fastener joints

A method for joining dissimilar materials is provided. The method includes a solid-state joining process in which a rivet is plunged into a predrilled hole in a top workpiece. When the rivet contacts the bottom workpiece, ultrasonic vibration by oscillatory motion of a sonotrode, such as horizontal, vertical, or rotational motion, creates frictional heat at the interface between the rivet and the lower workpiece. With the aid of frictional heat and axial compression, metallurgical bonding is achieved at the interface between the rivet and the bottom sheet, while being below the melting temperature of the bottom workpiece. The sonotrode is retracted while the rivet remains.

Ultrasonic rivet joining of dissimilar materials

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Oak Ridge, TN, United States of America

Yong Chae Lim