Improvement of Microstructure, Mechanical Properties and Corrosion Resistance of Cast Al–12Si Alloy by Friction Stir Processing

Friction stir processing (FSP) was applied to casting and non heat-treated strengthening of Al–12Si aluminum alloy in order to enhance the mechanical properties by improving the microstructure. Moreover, the corrosion resistance of FSPed Al–12Si alloy is also examined. The results indicate that intense plastic deformation during FSP effectively results in the grain refinement of Al–12Si alloy, uniform distribution of Si particles and elimination of cast porosities, and the microstructures of Al–12Si alloy are significantly improved. The microhardness, tensile strength and elongation are increased to 57.15 HV, 159.39 MPa and 9.87% after FSP, respectively, The surface fracture of the FSPed tensile specimen exhibits a typical ductile dimple-fracture. Grain-boundary strengthening and dispersion strengthening of Si particles play important roles in enhancing the mechanical properties. Meanwhile, compared with cast alloy, FSPed Al–12Si alloy has more excellent corrosion resistance.