Investigation of tool offset on mechanical properties of dissimilar AA6061-T6 and AA7075-T6 joint in parallel FSW process

This paper presents a new two-pass friction stir welding (FSW) implementation called parallel friction stir welding (P-FSW). This process is classified into two categories: Advanced parallel friction stir welding (AP-FSW) and retreating parallel friction stir welding (RP-FSW). The effects of three parameters named the type of process, tool offset in first pass, and tool offset in the second pass on tensile strength of AA6061-T6 and AA7075-T6 joint in FSW have been investigated experimentally. To design experiments, optimization, and analyzing the results, response surface methodology (RSM) has been used. Quantitative and qualitative variables have been considered in five and two levels, respectively. Based on obtained results, it has been observed that tool offset in the second pass, type of process, and tool offset in the first pass have the most effect on tensile strength of welded joint, respectively. In both AP-FSW and RP-FSW processes, the maximum tensile strength occurred at the maximum value of tool offset in the second pass and minimum value of tool offset in the first pass. The maximum joint efficiency of AP-FSW and RP-FSW processes with respect to AA6061-T6 were obtained 83.1% and 95.4%, respectively.