Copper strips (0.1mm thick) were used as markers to investigate the metal flow during friction stir welding.After welding,radiography and metalurgical sectioning were used to investigate the marker movement.The scope of this investigation is to evaluate the effect of shoulder and probe on the material flow and oxide in different welding parameters.The results of this study indicate that the shoulder produces a grind effect and the probe produces an effective fragmentation and dispersion,on the other hand,with the increase of hoat input,the effect of fragmentation and dispersion is decreased.