The aluminum alloys are widely used due to their light weight, the moderate strength and good corrosion resistance. The main applications include food processing equipment, chemical containers, aerospace and railway transport systems. The objective of this study is to compare the microstructure and fatigue behavior of Al 6061 T-6 and Al 6082 T-6 alloys welded by metal inert gas (MIG) and friction stir (FS) welding techniques. The tensile strength of Al 6061 T-6 and Al 6082 T-6 alloys were analyzed for both welding technique, which mainly depends on welding parameters used during welding process. The Grain size and microstructures of the MIG & FS weld joints of Al 6061 T-6 and Al 6068 T-6 have been studied at various welding process parameters. The microstructure study was carried out by using metallurgical microscope with image analyzer system. The micro hardness study was carried out by using digital vickers micro hardness tester for both weld joint materials.