Pre and post annealing effect on dissimilar friction stir welding of Al 5083/6063 using new pedal shape pin tool

In the present work dissimilar friction stir welding (DFSW) is performed using a newly developed pedal shape tool at selected parameters to produce joints with good joint efficiency due to pulsating effect and superior stirring action of the tool in the nugget zone (NZ). Dissimilar Al 5083/6063 plates of 6.35mm thickness were welded using friction stir welding (FSW) at variable tool rotational speed ranging between 800 rpm to 1200 rpm and a constant feed rate of 25 mm/min and the weld joints were analysed for mechanical properties and microscopy of fractured surface. Al 5083 was kept on the advancing side during the process and results in terms of Tensile strength (TS), yield strength (YS) and hardness of nugget zone (NZ) were compared for pre- annealed (PRA) and post- annealed (POA) plates at 250⁰C and 300⁰C respectively. Defect free joint were observed at 1200 rpm for post annealed plates which represents 90% tensile strength of similar 5083/5083 with 30% increase in hardness at nugget zone. Fracture morphology analysed through scattered electron morphology (SEM) images also represents superior strength and ductility combination at 1200 rpm. (paper)