Abstract: This research made an effort to find the resistivity of a cylindrical shape tool pin on 5 different materials such as AA6061 alloy, AA7075 alloy, AA6061 reinforced Activated Carbon (AC) composite, AA7075 reinforced AC and AA6061/AC-AA7075/AC dissimilar joints. The FSW process parameters like spindle speed, axial load, tilt angle and tool pin profile are taken as constant and the process are carried out in five different materials. Ultimate Tensile Strength and Hardness test are taken in the welded joints to validate the best joint. The defect free joint were obtained in the AA6061 reinforced activated composite plates of similar joint. Microstructure and EDAX test are taken in the best joint based on the mechanical test results.