**Abstract**

Aluminum and its alloys have gained much interest in advanced industrial applications due to its excellent mechanical properties. Welding is one of prominent fabrication technique which has to be performed to make assembling of different parts to create one complete product. Welding of aluminum alloys (al) using traditional welding methods is difficult task due to un-weldability of aluminum alloys, more defects in weldment, presence of aluminum oxide film, etc. Friction stir welding (FSW) is a novel welding technique which was developed specially to join the aluminum alloys without melting of materials to be joined. Achieving the good qualities of welded joint with enhanced efficiency of the FSW process needs, proper understanding of principles of FSW. In the present chapter, various aspects of FSW of aluminum alloys related to effects of process welding parameters and temperature distribution during welding on mechanical and metallurgical properties of weldment has been presented. Extending applications of FSW in joining of dissimilar aluminum alloys and welding of al alloys with other materials has also been discussed. Concluding remarks are drawn from the study. From the study, it is stated that FSW is suitable for mass production welding method for joining of similar/dissimilar aluminum alloy materials in large quantity of similar products.

**Keywords:** friction stir welding, aluminum alloys, mechanical properties, metallurgical properties, dissimilar welding
