ABSTRACT Influence of the rotational speed can be clearly seen by using field-emission scanning electron microscopy (FE-SEM). The influence of rotating speed on macro and microstructures, hardness, shear performance and failure mechanism of friction stir welding on AA7075-T6 Al alloy with a thickness of 5 mm was investigated. At the lowest rotational speed, the data show a significantly closer hardness distribution in the AA7075-T6 Al alloy plates used during the friction stir welding process. The presence of the Fe- compounds was observed in the fracture surface of the nugget zone through the microstructure analysis. In this experimental investigation H-13 steel tool is used for friction stir welding process.