Aluminum-Magnesium alloy AA5083 is used extensively as a structural material in aerospace, automobile and marine applications. Fusion welding processes such as metal inert gas. (MIG) welding and tungsten inert gas (TIG) welding are widely used in fabrication of this alloy. Fusion welding processes generally result in lower joint efficiencies mainly due to defects such as porosity, large columnar grain structure, loss of strain hardening effect in fusion zone and heat affected zone and loss of magnesium due to evaporation. Friction Stir (FS) welding is a solid state welding process which has been proved to solve the above mentioned problems. In this study Bead-on-Plate (BoP) welds were made on 5 mm thick plates of AA5083 using both tungsten inert gas and friction stir welding processes. Studies using light microscopy revealed that FS welding results in finer grains in the weld zone. Tensile testing of the joints revealed that FS welding results in superior tensile properties compared to TIG welding process. The drop in hardness in the weld zone is higher for the TIG welding. The depletion of magnesium due to evaporation in the fusion zone of TIG welds were found to be significantly higher compared to that in FS welds. It is concluded that Friction Stir Welding process resulted in significantly stronger joints and is more suitable to join AA5083. Copyright © 2013 ASM International® All rights reserved.