A novel friction welding technique based on a vortex material flow is developed to obtain linear welds. In this technique, a stir bar that has the identical material with the workpiece together with a holder is used to produce a vortex material flow within the workpiece via rotationally rubbing the workpiece's top surface. In this study, the process characteristics of this technique were exposed by employing 6061-T6 aluminum alloy as experimental material. Through changing the rotation and welding speeds, the effect of welding parameters on weld quality was investigated. The experimental results show that defect-free joints can be obtained at moderate rotation speeds and lower welding speeds. Too high rotation speed results in the interface slip between the workpiece and the stir bar. Too high welding speed or too low rotation speed leads to a lack of penetration defect occurring in welds. Equiaxed grains are observed in the weld center. They are evolved through continuous dynamic recrystallization and dynamic recovery. The average grain size gradually increases with the tool rotation speed increasing. The microhardness distribution on the joint transverse cross-section presents a "W" shape. The lowest hardness value together with the fracture location occurs in the heat affected zone. However, for the joints with lack of penetration, the fractures occur in the weld nugget zone. [ABSTRACT FROM AUTHOR]