Effect of multi-pass friction stir processing on the tensile strength of AA1100 aluminum reinforced with beach sand particles

Abstract Aluminum offers several advantages, including low density, excellent corrosion resistance, good workability, high strength, and superior thermal conductivity. However, its relatively low strength and stiffness limit its applications in certain structural uses. Friction Stir Processing (FSP) is a promising technique for enhancing the mechanical properties of metallic materials. Multi-pass FSP is specifically employed to improve the distribution of reinforcement particles within the processed zone. The aim is to investigate the effect of multi-pass FSP (1, 2, 3, and 4 passes) on the physical and mechanical properties of AA1100 reinforced with beach sands. The transverse speed and pin depth were kept constant throughout the process. Macrostructure, microstructure, and fracture morphology were analyzed using optical microscopy and Scanning Electron Microscopy (SEM), while tensile properties were measured using a Universal Testing Machine (UTM). SEM observations revealed that increasing the number of FSP passes enhanced the homogeneity of particle distribution, with the most uniform dispersion observed at 2 passes. The highest tensile strength, 144.40 MPa, was also achieved at 2 passes, although still below that of the base metal. These findings suggest that two-pass FSP provides the optimal balance between reinforcement dispersion and mechanical performance in AA1100 aluminum reinforced with natural ceramic particles from beach sands.