Friction stir welding (FSW) has become a favourite choice in the joining process of light weight metals. In FSW the material joining is taken place at the solid state. The process is carried out by inserting a rotating tool traversing along the faying surfaces of the material to be joined. It offers nearly defect free welds with minimized distortion and fine grain structure. However, the mechanism of welding and the process parametric combination for welds with consistent and reliable results are not clearly established. Even though FSW offers many advantages over the conventional welding processes, it is considered to be a slow process from a commercial point of view. Efforts to gather a suitable combination of parameters to produce good welds were mostly confined to lower linear speeds. There exists an ambiguity in the determination of the process parameters to produce reliable welds at higher welding speeds. Efforts to increase the welding speed resulted in defect generation because of insufficient heating during welding. .Considering the above requirements, AA2024 (Al-Mg alloy) and AA6061-T6(Al-Mg-Si) alloys appear to be highlysuitable for the deep- sea mining structures. Both these classes of alloys have a proven history of successful use in deep sea mining and other and marine applications.