Experimental Study on Wear Performance of Dissimilar Aluminium Alloy FSW Joints Optimized by RSM and Desirability Approach

Abstract

This study aimed to optimize the dry sliding wear performance in a pin-on-drum setup of friction stir welding (FSW) processed dissimilar AA5052 and AA2014 aluminium alloys using a systematic approach using Response Surface Methodology with a Box–Behnken Design. The investigation focused on examining the interplay between four critical wear test parameters—normal force, friction distance, sliding velocity, and the geometry of the FSWed specimen (Square, Triangle, and Cylinder Pin)—and their effects on wear rate and coefficient of friction (COF), the key indicators of tribological performance. The results of analysis of variance revealed that normal force and friction distance exerted the most significant impact on both responses, with higher levels of these parameters generally leading to increased wear and friction. Sliding velocity (0.5–1.5 m/s) had a non-linear effect on wear rate (minimal at 1 m/s) and reduced COF by 6%–8% at higher velocities, though these effects were statistically insignificant compared to normal force and friction distance. Notably, the geometry of the FSWed specimen exhibited a significant influence, with the square pin generally showing lower wear and friction compared to other pins. This optimization process yielded the following specific settings: normal force of 5.29818 N, friction distance of 790.3559 m, sliding velocity of 1.4688445 m/s, and the use of a square pin as the FSWed specimen. The deviations between predicted and experimental values were 15.65% for wear rate and 10.76% for COF—both within acceptable limits for tribological analyses. Microstructural analysis revealed dynamic recrystallization in the stir zone, producing refined grains and a uniform dispersion of Al₂CuMg precipitates that enhanced hardness and wear resistance. A comparison of worn surfaces under maximum-wear and optimized conditions revealed a transition from severe abrasive wear with significant material removal to a regime of milder abrasion with reduced surface damage.