Optimization of Dissimilar Friction Stir Welding Process Parameters of AA5083-H111 and AA6082-T6 by CCD-RSM Technique

The non-heat-treatable aluminium alloy AA5083 is used widely for marine applications because of its high resistance to sea water and industrial chemical environments. The heat-treatable AA6082 is regarded as structural material exhibiting medium strength and good resistance to corrosion and occupies incredible applications in construction industry. The joining of these alloys is bit challenging in the fusion welding process because of inevitable welding defects like porosity, cracks, distortion. The friction stir welding (FSW) is a potential solid-state joining process which is found more appropriate for such alloys. In this study, dissimilar materials such as AA5083-H111 and AA6082-T6 are selected for the FSW and based on design of experiments 31 trials were chosen with four varying input factors (tool pin profile, tool rotational speed, welding speed and axial force) at five levels to optimize the output responses, namely ultimate tensile strength (UTS) and percentage of elongation (POE). The central composite design (CCD) technique with response surface methodology (RSM) is applied using Design of Expert Version 11 software to develop second-order linear regression quadratic mathematical models using analysis of variance (ANOVA) in order to establish the relationship between input parameters and output responses. Further the confirmation tests revealed that the joints fabricated using tapered square pin profile yield better tensile strength and elongation when compared to other profiles.