Residual stress and deformation mechanism of friction stir welded aluminum alloys by nanoindentation

► We applied nanoindentation on welded Al-alloys for residual stresses investigation. ► The microstructure of weld zone appears to be dominated by recrystallisation. ► The weld properties were dominated by thermal rather than mechanical deformation by the tool. ► The residual stresses are revealed for both advancing and retreating side of welds.