Microstructure, Micro-Hardness, and Corrosion Resistance of Commercial Purity Al Processed by Hollow-Cone High-Pressure Torsion

Hollow-cone high-purity commercial Al prepared using copper mold suction casting method is annealed at 600 degrees C, then processed by high-pressure torsion of 0.25 and 0.5 revolutions to produce ultrafine-grained materials. Microstructure, micro-hardness, and corrosion resistance in 3.5% NaCl solution are investigated in this paper. The grain size of the deformed Al after 0.25 and 0.5 revolutions are 1.16 and 0.73 mu m, respectively, which are smaller than that of the annealed specimen of 33.46 mu m determined using electron backscatter diffraction. The micro-hardness of the deformed Al is two-times larger than that of the annealed specimen. In addition, corrosion resistance of the deformed Al is higher than that of the annealed specimen, which is verified by polarization tests and scanning electron microscopy.