Process Developments in FSW

Abstract

FSW and processing have largely evolved in recent years in terms of process knowledge, materials processed and industrial applications. Considering process developments friction stir has been studied in an hybrid welding process associated with electric current for welding Al based alloys. In this variant a temperature increase due to Joule effect was seen to improve the viscoplasticity of base material without affecting metallurgical characteristics, reducing lack of penetration, which is detrimental for fatigue resistance. Diffusion welding triggered by FSW, named friction stir diffusion welding (FSDW) has also been investigated to join materials with very distinctive properties as copper to stainless steel preventing the formation of brittle intermetallics and improving joining efficiency using downward force of 5,500 N, rotation speed of 1,800 rpm and travel speed of 90 mm/min. The same variant was tested to produce sandwich, or composite, materials as Al reinforced with NiTi ribbons taking advantage of the high conductive soft Al material and the damping capacity and high mechanical resistance shown by NiTi. A good embedment of the reinforcing material under appropriate processing conditions was seen due to the viscoplastic material flow around the NiTi. This paper aims at presenting some applications involving FSW and its variants in distinct industrial applications.