Optimized Parameter for Butt Joint in Friction Stir Welding of Semi-Solid Aluminum Alloy 5083 Using Taguchi Technique

The semi-solid metal (SSM) 5083 aluminum alloy was developed for part manufacturing in the marine shipbuilding industry. This study aimed to optimize the parameters for the friction stir welding process of SSM 5083 aluminum alloy using the Taguchi and analysis of variance (ANOVA) techniques. Our analyses included tensile strength, hardness value, and the microstructure. The results revealed that the optimal parameters obtained for the tensile strength and hardness value in the stir zone (SZ) were A1B1C2 (1000 rpm, 10 mm/min, with a threaded cylindrical tool) with a tensile strength of 235.22 MPa and A2B1C2 (1200 rpm, 10 mm/min, with a threaded cylindrical tool) with a hardness value of 80.64 HV. According to the results obtained by ANOVA, it was found that the welding speed was the most significant process parameter in terms of influencing the tensile strength. Contrarily, no parameter influenced the hardness at a 95% confidence level. The examination using scanning electron microscopy (SEM) and an energy dispersive X-ray spectroscope (EDS) revealed an elongated grain structure and a void defect at the pin tip on the advancing side (AS) in the SZ. The particle distribution was uniform with Al2O3 and small porous SiO2 phases. Moreover, the quantities of C, O, Al, F, and Mg decreased.