On the material flow in FSW of T-joints: Influence of geometrical and tecnological parameters

Abstract

Friction stir welding (FSW) now definitively reached a large interest in the scientific community and what is more in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The latter aspects are relevant also with reference to joints characterized by a complex geometry. What is more, advanced FEM tools permit to develop effective engineering of the processes; quantitative results can be acquired from numerical simulations once basic information, as the process mechanics and the material flow, are certain. Material flow plays a fundamental role in FSW since it determines the effectiveness of the joints or, in turn, the insurgence of defects. In the paper, the material flow in the FSW of aluminum alloys T-joints is investigated at the varying of the most relevant technological and geometrical parameters with numerical simulations and experiments. In particular, to investigate the metal flow, a wide campaign of experimental tests and observations was developed utilizing a thin foil of brass as marker, placed at the interface of the two blanks to be welded. Some relevant conclusions on the process mechanics and on the actual material flow determining the material bonding are outlined, permitting an insight of the FSW of T-joints.