Corrosion and tribological behaviour of Friction Stir Processed AA2024-T351 alloy

AA2024-T351, a heat treatable aluminum alloy, has a high strength to weight ratio and good fracture resistance and has application mainly in the aircraft and aerospace sector. However, the alloy is susceptible to high corrosion because of the secondary phases (Al₂Cu) present in the matrix. With an objective to increase the corrosion and wear resistance, Friction Stir Processing is applied to engineer the morphology and dispersion of the Al₂Cu phase in the alloy. The friction stir processing trials are performed by varying the tool rotation speed, tool traverse speed, and shoulder diameter, as the properties of the friction stir processed region depend on the proper selection of process parameters. A hybrid linear-radial basis function model is developed to explore the effect of tool rotation speed, tool traverse speed, and shoulder diameter on the grain size, microhardness, corrosion rate, wear rate, and corrosion potential of the friction stir processed AA2024-T351 alloy. The predominant corrosion mechanism and wear regimes in AA2024-T351 alloy are understood from the characterization study on the surface morphology and elemental analysis of the corroded and worn specimens. The optimum friction stir processing parameters that improve the grain refinement, microhardness, corrosion resistance and wear resistance of AA2024-T351 alloy are established.