Material flow in FSW of AA7075-T6 butt joints: Numerical simulations and experimental verifications

Friction stir welding (FSW) has reached a large interest in the scientific community and in the recent years also in the industrial environment, owing to the advantages of such solid state welding process with respect to the classic ones. Advanced finite element method tools are needed in order to develop an effective engineering of the processes; quantitative results can be acquired from numerical simulations once the basic information such as the material flow is certain. A 3D Lagrangian implicit coupled rigid viscoplastic model has already been developed by the authors to simulate FSW of butt joints. In the present paper the material flow in the FSW of AA7075 - T6 butt joints is investigated on 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 has been developed utilising a thin foil of copper as marker.