Abstract: A process for joining two or more overlapping metal workpieces includes providing a fastener which is made of metal having a melting point temperature at least as great as that of the workpieces. The fastener is rotated about its central axis and is axially advanced at a predetermined advance rate into engagement with the workpieces so as to cause plasticization of the workpieces at the interface with the fastener, and to cause the fastener to axially penetrate through substantially the entire thickness of the workpieces. The rotation of the fastener is then stopped, and the plastic zone which surrounds the fastener cools to form a metallurgical bond with the fastener. The resulting fastened joint is mechanically superior to conventional mechanically fastened joints made by rivets and the like.