Effect of friction stir welding parameters on the microstructure and mechanical properties of AA7075/YSZ composite joints

This study presented the friction stir welding (FSW) of AA7075/YSZ composite. The process was conducted by employing several rotational speeds (ω) (800 rpm, 1000 rpm, and 1200 rpm) and traverse speeds (v) (25 mm/min, 50 mm/min, and 75 mm/min). Various parameters were then primarily analysed on this AMC, including weldability, microstructure, mechanical behaviour, and fractography. The microstructure of the welded joints was examined using an optical microscope (OM) and a field emission scanning electron microscope (FESEM). This study then assessed the correlation between the welding parameters and mechanical properties using three test types: (i) tensile test, (ii) three-point bending test, and (iii) Vickers microhardness measurement. A tool constructed using high-speed steel with a cylindrical pin profile was also utilised. Consequently, the defect-free sound welds were observed with equiaxed grains at the nugget zone (NZ). The mechanical property test also indicated a high efficiency level in the joints. Notably, the maximum tensile and bending strength were achieved when ω and v were 1000 rpm and 25 mm/min, respectively. The NZ also demonstrated higher microhardness than other zones, in which the highest microhardness of 300 Hv was achieved when ω and v were 1200 rpm and 75 mm/min, respectively.