Corrosion and Tribological Characteristics of Friction Stir Processed Aluminium Alloy AA5052

Abstract

Friction stir processing (FSP) is a solid-state and effective process for surface modification of aluminium alloys. In this study the AA5052 alloy, widely used in marine applications, has been subjected to FSP. The FSP trials have been carried out by altering the FSP process parameters (tool rotation speed, tool traverse speed, and shoulder diameter). The friction stir processed specimens have been characterised / tested for microstructure, microhardness, sliding wear, immersion corrosion, and electrochemical corrosion. The hybrid polynomial – radial basis function-based models have been developed to determine the relationship between the process parameters and the evaluated properties. Furthermore, the optimum parameters for obtaining high hardness, wear resistance, and corrosion resistance have been determined. Microstructure evaluation in the friction stir processed specimens has shown refinement and uniform dispersion of β particles throughout the α-Al matrix. The results show that the improvement in properties is a result of the homogeneous dispersion of secondary β phase particles in the matrix. Friction stir processing of AA5052 alloy has improved hardness by ~14.5%, wear resistance by ~83%, and corrosion resistance ~87%. The optimum process window for friction stir processing of AA5052 alloy is tool rotation speed between 500 rpm and 900 rpm, tool traverse speed between 10 mm/min and 30 mm/min, and tool shoulder diameter of 18 mm and 21 mm.