Finite element simulation of microstructure evolution during friction stir welding of automotive aluminum parts

7000 series Aluminum alloys are widely used in the automotive industries for structural lightweight components due to their exceptional high strength to weight ratio. However, this class of aluminum alloy is difficult to join by conventional fusion welding techniques so Friction stir welding (FSW) widely is used for welding this alloys. The process has been demonstrated to be effective and is currently industrially utilized for materials difficult to be welded or “un weldable”, especially aluminum and magnesium alloys. In this paper in order to predict the average grain size occurring in FSW of AA7050 plates due to the dynamic recrystallization (DRX) phenomena due to the welding process, a microstructure evolution model have been implemented in 3D fully coupled thermo-mechanical FEM in which the tool – work piece interaction in FSW of butt joint was investigated.